Blood sugar after eating

Sugar and Your Body

Why are high blood sugar levels bad for you? Glucose is precious fuel for all the cells in your body when it’s present at normal levels. But it can behave like a slow-acting poison.

  • High sugar levels slowly erode the ability of cells in your pancreas to make insulin. The organ overcompensates and insulin levels stay too high. Over time, the pancreas is permanently damaged.
  • High levels of blood sugar can cause changes that lead to a hardening of the blood vessels, what doctors call atherosclerosis.

Almost any part of your body can be harmed by too much sugar. Damaged blood vessels cause problems such as:

  • Kidney disease or kidney failure, requiring dialysis
  • Strokes
  • Heart attacks
  • Vision loss or blindness
  • Weakened immune system, with a greater risk of infections
  • Erectile dysfunction
  • Nerve damage, also called neuropathy, that causes tingling, pain, or less sensation in your feet, legs, and hands
  • Poor circulation to the legs and feet
  • Slow wound-healing and the potential for amputation in rare cases

Keep your blood sugar levels close to normal to avoid many of these complications. The American Diabetes Association’s goals for blood sugar control in people with diabetes are 70 to 130 mg/dL before meals, and less than 180 mg/dL after meals.

Know Your Blood Sugar Numbers: Use Them to Manage Your Diabetes

Checking your blood sugar, also called blood glucose, is an important part of diabetes care. This tip sheet tells you:

  • why it helps you to know your blood sugar numbers
  • how to check your blood sugar levels
  • what are target blood sugar levels
  • what to do if your levels are too low or too high
  • how to pay for these tests

Why do I need to know my blood sugar numbers?

Your blood sugar numbers show how well your diabetes is managed. And managing your diabetes means that you have less chance of having serious health problems, such as kidney disease and vision loss.

As you check your blood sugar, you can see what makes your numbers go up and down. For example, you may see that when you are stressed or eat certain foods, your numbers go up. And, you may see that when you take your medicine and are active, your numbers go down. This information lets you know what is working for you and what needs to change.

How is blood sugar measured?

There are two ways to measure blood sugar.

  • Blood sugar checks that you do yourself. These tell you what your blood sugar level is at the time you test.
  • The A1C (A-one-C) is a test done in a lab or at your provider’s office. This test tells you your average blood sugar level over the past 2 to 3 months.

How do I check my blood sugar?

You use a blood glucose meter to check your blood sugar. This device uses a small drop of blood from your finger to measure your blood sugar level. You can get the meter and supplies in a drug store or by mail.

Read the directions that come with your meter to learn how to check your blood sugar. Your health care team also can show you how to use your meter. Write the date, time, and result of the test in your blood sugar record. Take your blood sugar record and meter to each visit and talk about your results with your health care team.

What are target blood sugar levels for people with diabetes?

A target is something that you aim for or try to reach. Your health care team may also use the term goal. People with diabetes have blood sugar targets that they try to reach at different times of the day. These targets are:

  • Right before your meal: 80 to 130
  • Two hours after the start of the meal: Below 180

Talk with your health care team about what blood sugar numbers are right for you.

How often should I check my blood sugar?

The number of times that you check your blood sugar will depend on the type of diabetes that you have and the type of medicine you take to treat your diabetes. For example, people who take insulin may need to check more often than people who do not take insulin. Talk with your health care team about how often to check your blood sugar.

The common times for checking your blood sugar are when you first wake up (fasting), before a meal, 2 hours after a meal, and at bedtime. Talk with your health care team about what times are best for you to check your blood sugar.

What should I do if my blood sugar gets too high?

High blood sugar is also called hyperglycemia (pronounced hye-per-gly-see-mee-uh). It means that your blood sugar level is higher than your target level or over 180. Having high blood sugar levels over time can lead to long-term, serious health problems.

If you feel very tired, thirsty, have blurry vision, or need to pee more often, your blood sugar may be high.

Check your blood sugar and see if it is above your target level or over 180. If it is too high, one way to lower it is to drink a large glass of water and exercise by taking a brisk walk. Call your health care team if your blood sugar is high more than 3 times in 2 weeks and you don’t know why.

What should I do if my blood sugar gets too low?

Low blood sugar is also called hypoglycemia (pronounced hye-poh-gly-see-mee-uh). It means your blood sugar level drops below 70. Having low blood sugar is dangerous and needs to be treated right away. Anyone with diabetes can have low blood sugar. You have a greater chance of having low blood sugar if you take insulin or certain pills for diabetes.

Carry supplies for treating low blood sugar with you. If you feel shaky, sweaty, or very hungry, check your blood sugar. Even if you feel none of these things, but think you may have low blood sugar, check it.

If your meter shows that your blood sugar is lower than 70, do one of the following things right away:

  • chew 4 glucose tablets
  • drink 4 ounces of fruit juice
  • drink 4 ounces of regular soda, not diet soda or
  • chew 4 pieces of hard candy

After taking one of these treatments, wait for 15 minutes, then check your blood sugar again. Repeat these steps until your blood sugar is 70 or above. After your blood sugar gets back up to 70 or more, eat a snack if your next meal is 1 hour or more away.

If you often have low blood sugar, check your blood sugar before driving and treat it if it is low.

What do I need to know about the A1C test?

The A1C test tells you and your health care team your average blood sugar level over the past 2 to 3 months. It also helps you and your team decide the type and amount of diabetes medicine you need.

What is a good A1C goal for me?

For many people with diabetes, the A1C goal is below 7. This number is different from the blood sugar numbers that you check each day. You and your health care team will decide on an A1C goal that is right for you.

How often do I need an A1C test?

You need to get an A1C test at least 2 times a year. You need it more often if:

  • your number is higher than your goal number
  • your diabetes treatment changes

How do I pay for these tests and supplies?

Medicare, Medicaid and most private insurance plans pay for the A1C test and some of the cost of supplies for checking your blood sugar. Check your plan or ask your health care team for help finding low cost or free supplies. Ask your health care team what to do if you run out of test strips. For more information about Medicare and diabetes, go to

What if I have trouble getting to my blood sugar goals?

There may be times when you have trouble reaching your blood sugar goals. This does not mean that you have failed. It means that you and your health care team should see if changes are needed. Call your health care team if your blood sugar is often too high or too low. Taking action will help you be healthy today and in the future.

John’s Story

At each visit, John and his health care team look at his A1C test results, his blood glucose meter and his blood sugar record to see if his treatment is working. At today’s visit, John’s A1C and blood sugar numbers are too high. John and his health care team talk about what he can do to get closer to his A1C and blood sugar goals. John decides he will be more active. He will:

  • increase his walking time to 30 minutes every day after dinner.
  • check his fasting blood sugar in the morning to see if being more active improves his blood sugar.
  • call his doctor in 1 month for a change in medicine if his blood sugar levels are still too high.
  • have his A1C tested again in 3 months to see if his new plan is working.

Things to remember

  • Check your blood sugar as many times a day as your health care team suggests.
  • Have your A1C checked at least 2 times a year.
  • Keep a record of your blood sugar and A1C numbers.
  • Take your blood glucose meter and blood sugar record to your visit and show them to your health care team. Tell your health care team how you think you are doing.
  • Call your health care team if your blood sugar is often too high or too low.

Work with your health care team and decide what changes you need to make to reach your blood sugar goals.
Download a copy of the NDEP’s Managing and Monitoring Diabetes to learn more about managing diabetes.

Common questions about blood sugar

How often should I test my blood sugar?
This is a very common question, and the answer isn’t the same for everyone. In general, you should test as often as you need to get helpful information. There’s no point in testing if the information you get doesn’t help you manage your diabetes.

If you’ve been told to test at certain times, but you don’t know why or what to do with the test results, then testing won’t seem very meaningful.

Here are some general guidelines for deciding how often to test:

  • If you can only test once a day, then do it before breakfast. Keep a written record so that you can see the pattern of the numbers. If you control your blood sugar by diet and exercise only, this once-a-day test might be enough.
  • If you take medicine (diabetes pills or insulin), you will probably want to know how well that medicine is working. The general rule is to test before meals and keep a record. If you want to know how your meals affect your blood sugar, testing about 2 hours after eating can be helpful.
  • Test whenever you feel your blood sugar is either too high or too low. Testing will give you important information about what you need to do to raise or lower your blood sugar.
  • If you take more than 2 insulin shots a day or use an insulin pump, you should test 4 to 6 times a day. You should test more often if you’re having unusually high or low readings, if you’re sick, under more stress than usual, or are pregnant. If you change your schedule or travel, you should also test your blood sugar more often than usual.

Talk to a member of your health care team about how often to test based on your personal care plan.

What should my test numbers be?
There isn’t one blood sugar target that’s right for everyone with diabetes. It’s important to work with your health care team to set goals that are right for you.

Some people aim for test results between 80 and 140. Others — for example, someone who is older and lives alone — might aim for a little higher target to reduce the chances of getting low blood sugar reactions. Your test goals should give you good results and also be safe and realistic for your age, health, and lifestyle.

Is it important to check after meals?
For most people with diabetes, testing before a meal is most helpful. That way they know if they took enough diabetes medicine to cover the previous meal, how much to take for the next meal, or how to adjust their meal plan for a test result that’s higher or lower than expected.

For many people, it’s also helpful to test after a meal. This can give you important information about how your blood sugar reacts to the foods you eat. It can also tell you if you’re taking the right dose of diabetes medicine (pills or insulin) to cover the amount of carbohydrate at each meal.

If you test soon after a meal, your blood sugar reading will probably be high. Even in people without diabetes, blood sugar readings after a meal can be as high as 180. If you want to check your blood sugar to see how a meal affected you, check about 1 to 2 hours after eating.

What should I do when my test result is too high?
If a single blood sugar reading is higher than you expected, try to figure out what might have caused it. Did you eat too much? Did you have a high-carbohydrate food? Did you forget to take your diabetes medicine, or did you take the wrong amount?

If your blood sugar is often too high, start to look for patterns. Is your blood sugar always high first thing in the morning? After you exercise? Before your evening meal?

Keep track of your blood sugar in a record book, and take it with you to see your doctor. A member of your health care team can show you how to look for patterns, what they mean, and what you can do to keep your blood sugar closer to your goal.

What should I eat when my blood sugar goes too low?
If your blood sugar is too low, you’ll need to eat or drink something with sugar right away. In general, blood sugar is too low if it gets under 70. Your doctor might set a different level for you.

Sugar or glucose will raise your blood sugar faster than other carbohydrates. It’s a good idea to have sugar cubes or glucose tablets with you all the time. Other good sources of fast-acting sugars include raisins, ripe bananas, carbohydrate-containing energy bars (not protein bars), fruit juice (such as apple or orange), and regular soda (not sugar-free).

You can raise your blood sugar about 50 milligrams of glucose per deciliter (mg/dl) with 15 grams of fast-acting carbohydrate. Examples include 4 glucose tablets, 1/2 cup of fruit juice, 6 or 7 Lifesavers candies, or 1/2 cup of regular soda.

How much carbohydrate you’ll need to correct your low blood sugar depends on how low your blood sugar is. Don’t overdo it. Eating more carbohydrate than you need to correct the low can make your blood sugar swing the opposite direction and get too high. Ask a member of your health care team to help you figure out how much carbohydrate you need when you have low blood sugar.

If my blood sugar goes too low, will I die?
If your blood sugar gets too low, you might pass out. But your life isn’t in danger unless you’re behind the wheel of a vehicle or operating a large machine. Always carry identification that tells people you have diabetes, in case someone finds you unconscious.

Many people wear a necklace or bracelet stating they have diabetes and what kind of medicine they take. Some people also carry a wallet card with their name, phone number, and the name and number of their doctor.

If you pass out from your blood sugar being too low, you might need someone to give you a glucagon shot. Glucagon is a medicine that raises blood sugar quickly. Ask your doctor for a prescription for a glucagon kit. Show your family, friends, co-workers, and exercise partners how to give you a glucagon shot. Ask them to practice with an insulin syringe and some saline (salt water) so they’ll know what to do if they ever need to help you.

Make sure your friends, family, and co-workers know to call 911. Medics might need to give you a shot of glucose in the vein.

How can my test results help me with my exercise plan?
Testing your blood sugar before and after you exercise can help you avoid extremely low and extremely high blood sugar levels that can happen when you exercise. If your blood sugar is less than 100, eat 15 grams of carbohydrate before you begin to exercise. Examples of a 15-gram carbohydrate snack include 6 saltine crackers, 5 vanilla wafers, 1 small apple, or 8 ounces of plain low-fat or non-fat yogurt.

Test your blood sugar every 30 to 45 minutes if you’re exercising for longer than 1 hour. If your blood sugar is less than 100, eat 15 grams of carbohydrate. Blood sugar levels will usually go down after a person has exercised, so it’s a good idea to test again an hour or so after you’ve finished exercising. If you had a long exercise session, you should keep checking your blood sugar during the next several hours to see if your blood sugar has continued to go down.

Why is my blood sugar sometimes higher after I exercise than it was before?
This happens most often in people who have to take insulin shots. If they don’t have enough insulin in their bloodstream at the time they start exercising, it will make their blood sugar levels go up. This is because the muscles will use up their glucose stores and send signals that they need more. The liver responds to these signals by releasing glucose into the bloodstream. This causes blood sugar levels to rise. Since there’s not enough insulin available to get the glucose out of the blood and into the muscles, the blood sugar level stays high.

If your blood sugar levels are always higher after exercising, talk to a member of your health care team about what you can do to keep this from happening.

Why is my fasting blood sugar sometimes much higher than my blood sugar was before I went to bed?
The body still needs insulin while you sleep to help move sugar from the bloodstream into cells. If the cells aren’t getting this sugar because there isn’t enough insulin, the body thinks there’s not enough sugar available. It responds by releasing stored sugar from the liver. That’s why people will have a higher blood sugar level in the morning.

One way to treat this is to take insulin that will last from 8 to 9 hours , before you go to bed for the night. It’s also important to make sure you’re eating a healthy evening meal, watching your serving sizes, and not eating too much before you go to bed.

How does eating fat or protein affect my blood sugar?
Most people won’t notice a rise in their blood sugar levels after eating a moderate amount of fat or protein. Fat and protein are usually digested slowly and change into sugar over several hours.

However, if a person eats a large amount of protein, it can cause a stronger but delayed rise in blood sugar. Examples of large fat or protein servings include several ounces of nuts, a large steak (8 to 12 ounces), or meals that include a lot of cheese, such as pizza.

Clinical review by Meredith Cotton, RN
Kaiser Permanente
Reviewed 01/03/2019

Several years ago, I wrote an article for Diabetes Self-Management about the management of high blood glucose after meals. It was called “Strike the Spike” and no article I’ve ever written has led to greater reader response. To this day, I still receive calls and e-mails thanking me for offering practical answers to this perplexing challenge. I’ve even been asked to speak on the topic at some major conferences. So when presented with the opportunity to readdress the issue, I jumped at the chance.


A lot has changed in recent years: we know more than ever about the harmful effects of after-meal blood sugar spikes, but we also have a number of potent new tools and techniques for preventing them. And now that I know how meaningful this topic is to so many people, I’ll do my absolute best to provide some answers.

What’s a spike, and why do they happen?

After-meal, or “postprandial,” spikes are temporary high blood glucose levels that occur soon after eating. It is normal for the level of glucose in the blood to rise a small amount after eating, even in people who do not have diabetes. However, if the rise is too high, it can affect your quality of life today and contribute to serious health problems down the road.

— Learn More About Blood Glucose Management >>

The reason blood glucose tends to spike after eating in many people with diabetes is a simple matter of timing. In a person who doesn’t have diabetes, eating foods containing carbohydrate causes two important reactions in the pancreas: the immediate release of insulin into the bloodstream, and the release of a hormone called amylin. The insulin starts working almost immediately (to move glucose out of the bloodstream and into cells) and finishes its job in a matter of minutes. The amylin keeps food from reaching the small intestine too quickly (where the nutrients are absorbed into the bloodstream). As a result, the moment blood glucose starts to rise, insulin is there to sweep the incoming glucose into the body’s cells. In most cases, the after-meal blood glucose rise is barely noticeable.

However, in people with diabetes, the situation is like that of a batter with very slow reflexes facing a pitcher who throws 98-mph fastballs: The timing is all fouled up. Rapid-acting insulin that is injected (or infused by a pump) at mealtimes takes approximately 15 minutes to start working, 60–90 minutes to “peak,” or reach maximum effectiveness, and 4 hours or more to finish working. (Afrezza, an ultra-rapid-acting inhalable insulin, begins working within 12–15 minutes of inhaling it, peaks at about 30 minutes, and lasts for about 3 hours.) Meanwhile, amylin is either produced in insufficient amounts or not at all, so the movement of food from the stomach to the intestines is not slowed the way it should be. As a result, food digests even faster than usual. This combination of slower insulin and faster food can cause the blood glucose level to rise quite high soon after eating. Once the mealtime insulin finally kicks in, the high is followed by a sharp drop.

Why are blood glucose spikes a problem?

Even though after-meal blood glucose spikes are temporary, several spikes a day, day after day, can raise your glycosylated hemoglobin, or HbA1c level, and a high HbA1c level has been shown to raise the risk of long-term diabetes complications.

Your HbA1c test result reflects your average blood glucose level for all times of day (before and after meals) over the past two to three months, with the more recent weeks influencing the result more than earlier weeks. So if your pre-meal blood glucose average is 130 mg/dl for a given three-month period, and your post-meal average is 240 mg/dl, your HbA1c will probably reflect an overall average somewhere in the middle of these two numbers.

Interestingly, research has shown that for people with an HbA1c below 7.5%, post-meal blood glucose readings have a greater influence on HbA1c than pre-meal readings. In other words, lowering your pre-meal readings will only get you so far. If you want your HbA1c level to be as close to normal as possible, you need to pay attention to your after-meal numbers as well.

The long-term effects of high blood glucose levels after meals have been studied extensively. For people with Type 1 diabetes, significant after-meal rises have been shown to produce earlier onset of kidney disease and to accelerate the progression of existing retinopathy, the eye problem most commonly associated with diabetes. In people with Type 2 diabetes, high blood glucose after meals is a risk factor for cardiovascular problems. Recently, post-meal spikes and glucose “variability” has been associated with diminished brain function and an increased risk of dementia.

But the problems are not limited to long-term complications. Any time blood glucose levels rise particularly high, even temporarily, quality of life suffers. Energy decreases, brain function falters, physical and athletic abilities become diminished, and moods become altered. An Australian study of young people with Type 1 diabetes indicated that short-term high blood glucose negatively affects thinking performance, coordination, and emotions and moods. A study conducted on people with Type 2 diabetes showed that sharp rises in blood glucose level slowed mental performance, lowered attention, reduced energy levels, and led to feelings of sadness and tension.

And don’t forget: What goes up must come down. The rapid blood glucose decline that usually follows a post-meal spike can cause false hypoglycemia symptoms. This is referred to as “relative hypoglycemia.” The sharp drop from a high blood glucose to a normal level can fool the brain into thinking that there is a crisis, and low blood glucose symptoms can result.

Additionally, the effects of a bout of post-meal high blood glucose do not go away immediately when blood glucose returns to normal. Each episode of high blood glucose can alter the way certain genes function, resulting in the production of harmful chemicals called free radicals, which cause inflammation and damage to the linings of the blood vessels for hours, if not days. So clearly, post-meal spikes represent a challenge worthy of attention.

Measuring spikes

The exact timing of a high blood glucose spike can vary from person to person and meal to meal. However, on average, after-meal peaks tend to occur about one hour and 15 minutes after the start of a meal. So checking your blood glucose (using a blood sample from a fingerstick) about an hour after finishing a meal should provide a good indication of how much of a spike is taking place. Check before and after breakfast, lunch, and dinner several times to determine how much of a spike is taking place after each of these meals. It is most common to see significant spikes after breakfast, but check after each meal at least a few times just to see what is happening.

A better way to measure post-meal patterns is by using a continuous glucose monitor (CGM). These systems, available from Medtronic, Dexcom, Abbott, and Senseonics, provide glucose readings every couple of minutes so you won’t miss the peak, whenever it happens to occur. They also produce trend graphs that make it easy to see exactly what is happening after meals. See example below:

Personal CGM systems can be purchased for long-term or ongoing use. Some specialized diabetes centers offer them on a temporary loaner basis just to get a sense of what is happening with your blood glucose at all times. CGM systems include a tiny disposable sensor filament placed just below the skin, a small transmitter attached to the sensor, and a receiver that displays your data. The receiver can take the form of a handheld device, an insulin pump, a smartphone, or even a smartwatch. The data from all of the systems is uploadable to a computer for analysis of the information.

Whether you use fingersticks or a CGM, when interpreting your numbers, take your pre-meal readings into account. A high or low reading before the meal will usually contribute to a higher reading after the meal. For example, a pre-meal blood glucose of 210 mg/dl followed by a 1-hour post-meal reading of 240 mg/dl shows just a 30-point rise, whereas a 110 mg/dl followed by a 240 mg/dl shows a 130-point rise. Lows before meals usually affect rates of digestion and may trigger a hormonal “rebound” to produce much higher readings.

So exactly how high is too high after a meal? There is no universal consensus on this issue. The American Diabetes Association recommends keeping blood glucose below 180 mg/dl one to two hours after the start of a meal. The European Diabetes Policy Group recommends keeping it below 165 mg/dl at the peak, and the American Association of Clinical Endocrinologists and the International Diabetes Federation recommend keeping it below 140 mg/dl after eating. However, no specific guidelines are provided by any of these groups for Type 1 versus Type 2 diabetes, insulin users versus non-users, or children versus adults.

Based on my experience, I recommend the following after-meal goals for the following groups. These numbers are generally achievable, lead to a decent HbA1c level, and do not interfere with daily quality of life:

    • Adults who take mealtime insulin: below 180 mg/dl
    • Adolescents (12–18): below 200 mg/dl
    • School-age children (6–11): below 225 mg/dl
    • Preschool-age and toddlers (5 or younger): below 250 mg/dl
  • People with Type 2 diabetes who do not take mealtime insulin: below 140 mg/dl

After-meal readings that are consistently above these levels should be addressed by you and your health-care team (see strategies in the sections below).

Another way to assess after-meal blood glucose control is with a blood test trade-named GlycoMark. The test measures the level of a specific type of sugar (1,5-anhydroglucitol, or 1,5-AG) that becomes depleted whenever the kidneys are spilling glucose into the urine; this typically occurs when blood glucose exceeds approximately 180 mg/dl. The test result reflects blood glucose levels over the prior one to two weeks. A low GlycoMark score means that you are spending considerable time with blood glucose levels above 180. So if your HbA1c is normal (or low) and your GlycoMark is also low, you are likely spiking quite a lot after meals.

Medical approaches to spike control

A common approach to lowering after-meal blood glucose spikes is to take more insulin. But unless blood glucose levels remain high for three to six hours after eating, taking more insulin is not going to solve the problem. In fact, increasing mealtime insulin will most likely result in low blood glucose before the next meal.

Here are some strategies that may work better:

Choose the right insulin. The right insulin program can make or break your ability to control after-meal spikes. In general, insulins and other medicines that work quickly and for a short time will work better than those that work slowly over a prolonged period.

For instance, rapid-acting insulin analogs (brand names Humalog, NovoLog, and Apidra), which start working 10–15 minutes after injection and peak in about an hour, will cover the after-meal blood glucose rises much better than Regular insulin, which takes 30 minutes to begin working and 2–3 hours to peak.

Newer ultra-rapid insulins, such as Fiasp (insulin aspart), works even faster, with an onset and peak occurring 8–10 minutes earlier than traditional rapid-acting insulins.

The way insulin is administered can dramatically affect its speed of action. Afrezza (insulin human inhalation power) is an inhaled insulin formulation that can be used at mealtimes. Because the dry powder is absorbed through the lungs (rather than having to go through the fat layer below the skin), its onset and peak are much earlier than injected insulin (it takes 12–15 minutes to begin working and peaks in about 30 minutes).

Research has also shown that injected insulin can work much faster when the injection (or infusion) site is warmed. This can be accomplished by rubbing the site, immersing in warm water, or exercising the muscle near the site. Warming the site causes the blood vessels near the skin to dilate, which allows the insulin to absorb more quickly. By the way, smoking causes the blood vessels to constrict, so quitting smoking might improve your post-meal blood sugar (in addition to helping you and those around you to live longer).

If you use a morning injection of NPH insulin to “cover” the carbohydrate eaten in the middle of the day, your blood glucose level after lunch and after any daytime snacks is likely to be very high. This is also the case if you take a premixed insulin (75/25, 70/30, or 50/50) twice daily. For fewer spikes, consider taking a rapid-acting insulin before each meal or snack and using a long-acting “basal” insulin such as Lantus, Levemir, Toujeo, or Basaglar for coverage between meals.

Time your bolus insulin properly. For people who take rapid-acting insulin at mealtimes, the timing of the bolus can have a huge impact on after-meal blood glucose levels. Boluses given too late to match the entry of glucose from dietary carbohydrates into the bloodstream can produce significant blood glucose spikes soon after eating. A properly timed bolus, on the other hand, can result in excellent after-meal control.

Unless you have gastroparesis (slowed stomach emptying, usually caused by nerve damage), it is best to give bolus insulin doses before eating. How long before? It depends mainly on what you are eating and on your pre-meal blood glucose level.

Figuring out the pre-meal blood glucose part is fairly straightforward: the higher your blood glucose, the earlier the bolus should be given. If your pre-meal blood glucose is well above your target, it is best to give the bolus and then wait at least 30 minutes before eating. Near your target blood glucose? Wait 15 minutes. Below target? Either take the bolus and eat right away, or take the bolus after eating to manage high blood glucose.

Does earlier bolusing make a difference? Absolutely. Research has shown that simply giving mealtime boluses before eating rather than after eating can reduce the post-meal spike by about 45 mg/dl.

Bolus for the basal. For people who use insulin pumps, one way to have more insulin working right after eating and less working several hours later is to give what John Walsh, coauthor of the Pumping Insulin books, calls a “super bolus.” This is done by substantially reducing the basal rate for 3 hours before eating, then adding the amount of insulin that wasn’t given as basal insulin to the normal pre-meal bolus. For example, if your normal basal rate in the morning is 0.6 units per hour, you could set a temporary basal rate of 10% (90% reduction), for the 3 hours before breakfast, then bolus an extra 1.8 units at breakfast.

Choose the right medication. Two classes of injectable hormones, GLP-1 agonists (exenatide , liraglutide , albiglutide , dulaglutide ) and amylin mimetics (pramlintide ), have powerful effects on post-meal blood sugar. Both GLP-1s and Symlin slow gastric emptying and keep carbohydrates from raising the blood sugar too quickly after meals. Symlin, which is a replacement for the amylin hormone (which is lacking in people with diabetes), also helps to diminish appetite and blunt post-meal glucagon secretion. GLP-1s blunt appetite and promote the growth of insulin-producing cells in the pancreas of those with Type 2 diabetes. So both can contribute to better post-meal high blood glucose control.

Your choice of oral medication can also impact your after-meal control. Sulfonylureas (glyburide, glipizide, glimepiride) stimulate the pancreas to secrete a little extra insulin throughout the day, without regard to meal timing. Because these medications fail to concentrate the insulin secretion at times when it is needed most, after-meal blood sugars can run very high. There are alternative medications called meglitinides (epaglinide , nateglinide ) which also stimulate the pancreas but do so in a much faster and shorter manner. When taken at mealtimes, meglitinides produce better after-meal high blood glucose control than sulfonylureas.

Another class of oral diabetes medications (alpha-glucosidase inhibitors) improve after-meal control by partially blocking the transport of sugars across the intestines and into the bloodstream. However, these medications can sometimes cause gas, bloating and stomach upset, so the pros don’t always outweigh the cons.

Lifestyle approaches

Like much of diabetes management, medicine is only part of the story in preventing after-meal spikes: Diet and exercise can play a role as well. Here’s how:

Think lower GI. As mentioned earlier, the glycemic index is a rating of how quickly a food raises the blood glucose level. While all carbohydrates (except for fiber) convert into glucose eventually, some forms do so much faster than others.

Many starchy foods (such as breads, cereals, potatoes, and rice) have a high glycemic index; they digest easily and convert into blood glucose quickly. However, some starchy foods (such as pasta, beans, and peas) have lower glycemic index values. Foods that have dextrose in them — such as glucose tablets and gel and candies such as SweeTarts, Smarties, Spree, Runts, Nerds, and AirHeads — tend to have a very high glycemic index, which could lead to high blood glucose levels. Table sugar (sucrose) and fructose (fruit sugar) have moderate glycemic index values, while lactose (milk sugar) is slower to raise blood glucose.

A number of books, notably Dr. Jennie Brand-Miller’s Glucose Revolution series, contain extensive information about the glycemic index, along with lists of glycemic index values for hundreds of foods.

As a general rule, switching to lower-glycemic-index foods will help to reduce your after-meal high blood glucose spikes. There are a number of characteristics that slow down the rate at which foods are digested and raise blood glucose. Here are some of them:

    • Foods that contain soluble fiber (such as legumes, oats, and psyllium) are digested more slowly than low-fiber carbohydrate foods and than foods that are high in insoluble fiber that has been finely ground, such as whole wheat flour.
    • High-fat foods are digested more slowly than low-fat foods.
    • Solids are digested more slowly than liquids.
    • Cold foods are digested more slowly than hot foods.
    • Under-ripe and undercooked foods are digested more slowly than fully ripe or well-cooked foods.
  • Whole foods (such as unprocessed grains, legumes, and dried beans) are digested more slowly than milled or processed foods.

Another food property that affects the rate of digestion is acidity. This is why sourdough bread has a much lower glycemic index value than regular bread. Research has shown that adding acidity to a meal in the form of vinegar (straight or consumed as part of a salad dressing or other condiment) can reduce the one-hour post-meal blood glucose rise by 50% or more.

This table shows some examples of lower-glycemic-index substitutes for common high-glycemic-index foods.

Split your meal. The amount you eat has the greatest effect on your blood glucose level after you eat. One way to lower your high blood glucose rise after meals, therefore, is to eat less. But you don’t have to starve: instead, save a portion of your meal for a “snack” one or two hours later. That way, you get all the food you need, but it doesn’t raise your blood glucose all at once.

If you use mealtime insulin, you should still give yourself your full mealtime dose before eating any of the meal. For example, if you normally have a bowl of cereal and juice for breakfast, you would take enough insulin to cover both, but then just eat the cereal for breakfast, and postpone the juice until mid-morning to combat high blood glucose.

Get moving. Physical activity after eating can reduce post-meal spikes in a number of ways. If you took insulin before your meal or snack, the enhanced blood flow to the skin surface caused by exercise is likely to make the insulin absorb and act more quickly. Muscle activity also diverts blood flow away from the intestines, resulting in slower absorption of glucose into the bloodstream. In addition, the glucose that does enter the bloodstream is likely to be used by the working muscles, rather than stored for later use.

How much activity is required to experience these benefits? Not much. Ten or 15 minutes (or more) of mild activity will usually get the job done. The key is to avoid sitting for extended periods of time after eating. Instead of reading, watching TV, or working on the computer, go for a walk, shoot some hoops, or do some chores. Try to schedule your active tasks (housework, yardwork, shopping, walking pets) for after meals. Also attempt to schedule your exercise sessions for after meals to lower high blood glucose. On “date nights,” resist the urge to sit and talk for hours or to head straight for a movie. Instead, go out dancing, bowling, or skating.

Prevent hypoglycemia. Low blood sugar is problematic in many ways. One of the body’s typical responses to hypoglycemia is to speed up the rate at which the stomach empties. That means food digests and raises blood glucose even more rapidly than usual. While this is certainly desirable when you’re low, it does contribute to post-meal spikes. Preventing hypoglycemia before meals and snacks, therefore, is yet another effective strategy for controlling post-meal blood glucose levels.

Time to strike high blood glucose!

Given the many short- and long-term benefits of post-meal blood glucose control, it is certainly worth the effort to start measuring and evaluating your after-meal control. If your blood glucose levels are higher than they should be, talk with your health-care team about new or different medical treatments that might help. And take a look at your personal choices in terms of food and activity. Even without a perfectly functioning pancreas, there is still a multitude of options for tackling those high blood glucose spikes!

Want to learn about additional strategies that may help reduce after-meal blood sugar? Read “Walking Significantly Reduces After-Meal Glucose,” “Vinegar Reduce After-Meal Glucose,” “Dealing With After-Meal Blood Sugar Spikes? Don’t Skip Breakfast,” and “Eat More Protein at Breakfast to Prevent After-Meal Blood Sugar Spikes.”

Hyperglycemia: When Your Blood Glucose Level Goes Too High

Hyperglycemia means high (hyper) glucose (gly) in the blood (emia). Your body needs glucose to properly function. Your cells rely on glucose for energy. Hyperglycemia is a defining characteristic of diabetes—when the blood glucose level is too high because the body isn’t properly using or doesn’t make the hormone insulin.

You get glucose from the foods you eat. Carbohydrates, such as fruit, milk, potatoes, bread, and rice, are the biggest source of glucose in a typical diet. Your body breaks down carbohydrates into glucose, and then transports the glucose to the cells via the bloodstream.

Body Needs Insulin
However, in order to use the glucose, your body needs insulin. This is a hormone produced by the pancreas. Insulin helps transport glucose into the cells, particularly the muscle cells.

People with type 1 diabetes no longer make insulin to help their bodies use glucose, so they have to take insulin, which is injected under the skin. People with type 2 diabetes may have enough insulin, but their body doesn’t use it well; they’re insulin resistant. Some people with type 2 diabetes may not produce enough insulin.

People with diabetes may become hyperglycemic if they don’t keep their blood glucose level under control (by using insulin, medications, and appropriate meal planning). For example, if someone with type 1 diabetes doesn’t take enough insulin before eating, the glucose their body makes from that food can build up in their blood and lead to hyperglycemia.

Your endocrinologist will tell you what your target blood glucose levels are. Your levels may be different from what is usually considered as normal because of age, pregnancy, and/or other factors.

  • Fasting hyperglycemia is defined as when you don’t eat for at least eight hours. Recommended range without diabetes is 70 to 130mg/dL. (The standard for measuring blood glucose is “mg/dL” which means milligrams per deciliter.) If your blood glucose level is above 130mg/dL, that’s fasting hyperglycemia. Fasting hyperglycemia is a common diabetes complication.
  • Postprandial or reactive hyperglycemia occurs after eating (postprandial means “after eating”). During this type of hyperglycemia, your liver doesn’t stop sugar production, as it normally would directly after a meal, and stores glucose as glycogen (energy sugar stores). If your postprandial (1-2 hours after eating) blood glucose level is above 180mg/dL, that’s postprandial or reactive hyperglycemia.

However, it’s not just people with diabetes who can develop hyperglycemia. Certain medications and illnesses can cause it, including beta blockers, steroids, and bulimia. This article will focus on hyperglycemia caused by diabetes.

Early Hyperglycemia Symptoms
Early symptoms of hyperglycemia, or high blood glucose (sugar), may serve as a warning even before you test your glucose level. Typical symptoms may include:

  • Increased thirst and/or hunger
  • Frequent urination
  • Sugar in your urine
  • Headache
  • Blurred vision
  • Fatigue

Ketoacidosis: When Hyperglycemia Becomes Severe for People with Type 1 Diabetes
If you have type 1 diabetes, it is important to recognize and treat hyperglycemia because if left untreated it can lead to ketoacidosis. This happens because without glucose, the body’s cells must use ketones (toxic acids) as a source of energy. Ketoacidosis develops when ketones build up in the blood. It can become serious and lead to diabetic coma or even death. According to the American Diabetes Association, ketoacidosis affects people with type 1 diabetes, but it rarely affects people with type 2 diabetes.

Many symptoms of ketoacidosis are similar to hyperglycemia. The hallmarks of ketoacidosis are:

  • High level of ketones in the urine
  • Shortness of breath
  • Fruit-smelling breath
  • Dry mouth

Additionally, stomach pain, nausea, vomiting, and confusion may accompany ketoacidosis. Immediate medical attention is highly recommended if you have any of these symptoms.

Some people with diabetes are instructed by their doctor to regularly test ketone levels. Ketone testing is performed two ways: using urine or using blood. For a urine test, you dip a special type of test strip into your urine. For testing blood ketones, a special meter and test strips are used. The test is performed exactly like a blood glucose test. If ketone testing is part of your self-monitoring of diabetes, your healthcare professional will provide you with other information including prevention.

Hyperosmolar Hyperglycemic Nonketotic Syndrome (HHNS): When Hyperglycemia Becomes Severe for People with Type 2 Diabetes
Hyperosmolar hyperglycemic nonketotic syndrome (HHNS) is very rare, but you should be aware of it and know how to handle it if it occurs. HHNS is when your blood glucose level goes way too high—you become extremely hyperglycemic. HHNS affects people with type 2 diabetes.

HHNS is most likely to occur when you’re sick, and elderly people are most likely to develop it. It starts when your blood glucose level starts to climb: when that happens, your body will try to get rid of all the excess glucose through frequent urination. That dehydrates your body, and you’ll become very thirsty.

Unfortunately, when you’re sick, it’s sometimes more difficult to rehydrate your body, as you know you should. For example, it might be difficult to keep fluids down. When you don’t rehydrate your body, the blood glucose level continues to climb, and it can eventually go so high that it could send you into a coma.

To avoid hyperosmolar hyperglycemic nonketotic syndrome, you should keep close watch on your blood glucose level when you’re sick (you should always pay attention to your blood glucose level, but pay special attention when you’re sick).

Talk to your healthcare professional about having a sick-day plan to follow that will help you avoid HHNS.

You should also be able to quickly recognize the signs and symptoms of HHNS, which include:

  • Extremely high blood glucose level (over 600 mg/dL)
  • Dry mouth
  • High fever (over 101ºF)
  • Sleepiness
  • Vision loss

Treating Hyperglycemia
Treating hyperglycemia is a matter of working on preventing it.

If your blood glucose level is consistently too high, talk with your doctor about what you can do to keep it in a more normal range. He or she may suggest:

  • Medication Adjustment: Your doctor may adjust your insulin (or glucose-lowering medication) dose or when you take it to help prevent hyperglycemia.
  • Meal Plan Help: A healthy diet and proper meal planning can help you avoid hyperglycemia. This includes eating often, watching intake of sugar and carbohydrates, limiting use of alcohol, and eating a diet rich in vegetables, fruit and whole grains. If you are having difficulty planning meals, talk to your doctor or dietitian.
  • Exercise: Regular exercise is important (even if you don’t have diabetes). Maintaining a healthy level of activity can help you keep your blood glucose level in a normal range.
    However, if you develop hyperglycemia and/or ketones are present in your urine, don’t exercise. Hyperglycemia and/or ketones in the urine mean exercise will cause your blood glucose to rise higher.

Preventing Hyperglycemia
The easiest way to prevent hyperglycemia is to control your diabetes. That includes knowing the early symptoms—no matter how subtle. Remember, there are many aspects of your diabetes care you can control:

  • Taking your insulin (or glucose-lowering medication) as prescribed
  • Avoiding consuming too many calories (i.e., sugary beverages)
  • Consuming the right types and grams of carbohydrates
  • Controlling stress
  • Staying active (exercising)
  • Going to your regularly scheduled doctor’s appointments

Hyperglycemia is a common complication of diabetes, but through medication, exercise, and careful meal planning, you can keep your blood glucose level from going too high—and that can help you in the long-run.

Keeping your blood glucose levels in the recommended ranges throughout the day will help you avoid long-term complications of diabetes, such as:

  • Eye damage
  • Heart attack—or other cardiovascular complications
  • Kidney damage
  • Nerve damage
  • Stroke
  • Problems with healing wounds

By maintaining your blood glucose levels—and avoiding hyperglycemia—you can reduce your risk of all these complications.

Updated on: 09/07/18 View Sources

What is a normal blood sugar level?

The answer to the question what is a normal blood sugar level is as follows:


Normal blood sugar 2 hours after meals
Normal for person without diabetes: Less than 140 mg/dl (7.8 mmol/L)
Official ADA recommendation for someone with diabetes: Less than 180 mg/dl (10.0 mmol/L)

Normal for person without diabetes: Less than 5.7%
Official ADA recommendation for someone with diabetes: Less than 7.0%

Source: American Diabetes Association

Blood sugar levels and diabetes

If you have diabetes, you may be wondering (or, have wondered at some point) what your blood glucose (sugar) “should” be. Hopefully your doctor, nurse practitioner, physician’s assistant or whoever diagnosed you has given you answers to that question. Unfortunately, though, not everyone is given glucose goals. Or in some cases, it may have been a long time ago, and they’ve since been forgotten. No worries — we’ll go over all that!

What is blood glucose, anyway?

Blood glucose, or sugar, is sugar that is in your blood (easy enough!). It comes from the food that you eat — foods that contain carbohydrate, such as bread, pasta and fruit are the main contributors to blood glucose. The cells in our bodies need glucose for energy — and we all need energy to move, think, learn and breathe. The brain, which is the command center, uses about half of all the energy from glucose in the body.

When things go awry

When we eat food, the pancreas (an organ that sits between the stomach and the spine) goes to work, releasing enzymes that help to break down food and hormones that help the body handle the influx of glucose. One of these hormones is insulin, and it plays a key role in managing glucose levels in the blood.

And here is where things can go wrong. If the pancreas doesn’t make enough insulin — or stops making it altogether, in the case of type 1 diabetes — glucose levels in the blood can rise too high. Another scenario is that the pancreas makes enough insulin but the cells have trouble using it properly, causing blood glucose levels to rise. This is called insulin resistance and is the hallmark of type 2 diabetes.

In the short term, high blood glucose levels can make you feel downright bad. Thirst, frequent trips to the bathroom, fatigue and weight loss are all symptoms of high blood glucose (hyperglycemia). If not treated, more serious issues can occur, such as diabetic ketoacidosis. Chronic high blood glucose levels can lead to complications such as heart, kidney and eye disease, as well as nerve damage. So, it’s all about the blood glucose.

How do you know what your blood glucose level is?

For the most part, you can’t “feel” what your blood glucose level is — unless it’s fairly high or it’s low. You may not even always have symptoms of either high or low blood glucose; in fact, many people with type 2 diabetes don’t have the usual symptoms of high blood glucose, and for this reason, it’s not uncommon for people to go undiagnosed for many years.

The best way to know your blood glucose level is to check it with a glucose meter. This means doing a fingerstick with a lancet and getting a drop of blood onto a test strip, then inserting the strip into the meter for a reading. Your doctor may be able to give you a meter free of charge, but you’ll likely need to pay for test strips and lancets. But check with your health plan, as there are likely one or two “preferred” meters that they want you to use.

Another way to know what your glucose levels are up to is to use a continuous glucose monitor, or CGM, which reads glucose in the interstitial fluid (the fluid between cells) about every 5 minutes. Continuous glucose monitoring is expensive and may or may not be covered by your health plan.

Now that you’re checking your blood glucose, what do the numbers mean?

Depending on your diabetes treatment plan, your doctor or diabetes educator may advise you to check once a week, once a day or up to 10 times a day (hint: if they don’t tell you, ask!). But what does it mean when you see a 67, 101 or 350 on your meter? And what is a “normal” blood sugar, anyway? Great questions! After all, if you don’t know what the numbers on your meter mean, it’s hard to know how you’re doing.

(Here’s where the term “normal” comes in. According to the Merriam-Webster dictionary, one definition of normal is “conforming to a type, standard, or regular pattern.” It’s a term that not everyone takes kindly to, because if you’re not “normal,” you might be considered “abnormal,” which means, “unusual in an unwelcome or problematic way.” Rather than thinking of your blood sugars as being normal or abnormal, you might think of them as being “in range,” “in target” or “at goal.”)

The American Diabetes Association (ADA) provides guidelines (not mandates) for blood glucose goals for people with diabetes, and the goals vary depending on when you’re checking your glucose:

• Fasting (before eating the first meal of the day) and before meals: 80–130 mg/dl (4.4–7.2 mmol/L)

• Postprandial (one to two hours after a meal): Less than 180 mg/dl (10.0 mmol/L)

By the way, these guidelines are for non-pregnant adults with type 1 or type 2 diabetes. Children, adolescents and pregnant women may have different goals.

Your blood glucose goals may be different, however. If you’re younger, have had diabetes for a shorter amount of time or are not taking any medicine for your diabetes, your glucose goals might be a little “tighter,” or lower. Likewise, your blood glucose goals may be higher than what ADA recommends if you’re older, have diabetes complications, or don’t get symptoms when your blood glucose is low.

Bottom line: talk with your health-care provider about the following:

• When to check your blood glucose
• How often to check your blood glucose
• What your blood glucose goals are (don’t forget to ask about your A1C goal, as well)

Know your numbers

Consider keeping a log of your glucose levels. You can use good old-fashioned pencil and paper, a spreadsheet, a logbook or a smartphone app to track your levels. If you’re not inclined to do this, your meter will capture up to a certain number of glucose values and let you download them to a computer for your viewing pleasure.

It’s important to look at all of your glucose values to get the big picture — not just a single point in time. By doing so, you can spot trends (for example, your fasting blood glucose levels are consistently above target or you tend to go low every afternoon around 4pm). Your numbers are information for both you and your health-care team to learn how your diabetes treatment plan (medication, food intake, physical activity) are working for you. Bring your logs or, at least, your meter to all of your regular provider visits and make sure your provider looks at your numbers.

Remember: If your blood glucose levels aren’t at goal, ask your provider or diabetes educator what you can do to tweak your diabetes treatment plan. Not every blood sugar that you check needs to be at target, but the closer you keep them within your target range, the lower the chance of complications. And the more often you check your blood glucose, the more information you have at your fingertips (literally) to do a course correction, if needed.

A Registered Dietitian and Certified Diabetes Educator at Good Measures, LLC, where she is a CDE manager for a virtual diabetes program. Campbell is the author of Staying Healthy with Diabetes: Nutrition & Meal Planning, a co-author of 16 Myths of a Diabetic Diet, and has written for publications including Diabetes Self-Management, Diabetes Spectrum, Clinical Diabetes, the Diabetes Research & Wellness Foundation’s newsletter,, and

Learn blood sugar basics with our free guide!

Interested in learning more about blood sugar? Check out our blood sugar chart and learn about using blood sugar monitoring to manage diabetes in “Managing Your Blood Glucose Ups and Downs.”

En Español: ¿Qué es Un Nivel Normal de Azúcar en Sangre?

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