Type 2 diabetes insulin

Injectable Insulin for Type 2 Diabetes: When, Why, and How

Here’s what you need to know about taking insulin in the short term and the long term.

Insulin for Short-Term Blood Sugar Control

Doctors use a blood test called a hemoglobin A1C test to measure average blood sugar control over a two- to three-month period.

The treatment target for most people with diabetes is an A1C of 7 percent or less; those with higher levels may need a more intensive medication plan.

“The American Association of Clinical Endocrinologists recommends starting a person with type 2 diabetes on insulin if their A1C is above 9 percent and they have symptoms,” said Mazhari.

Symptoms of type 2 diabetes include thirst, hunger, frequent urination, and weight loss.

Research published in February 2013 in the journal The Lancet Diabetes & Endocrinology reviewed several studies that focused on the temporary use of insulin to restore sugar control in people with type 2 diabetes.

The results showed that a two- to five-week course of short-term intensive insulin therapy (IIT) can induce remission in patients who are early in the course of type 2 diabetes. At three months after stopping the IIT, 66 percent of patients were still in remission, and at six months, 59 percent were still in remission.

Insulin for Long-Term Blood Sugar Control

“After 10 to 20 years, almost all patients with type 2 diabetes will need insulin,” Mazhari said.

“Once they lose most of the cells in the pancreas that make insulin, no other diabetes medication can help. They may have been on one, two, or three diabetes medications, but their A1C can no longer be kept in a safe range.”

Switching from numerous diabetes drugs to insulin can streamline your efforts.

Type 2 diabetes is a progressive disease, so treatment plans will change. When it’s not possible to meet blood sugar control goals with lifestyle changes or other medication, insulin is the next step.

The change can have upsides, particularly for patients who have been on a complicated regimen of three or four drugs, with lots of side effects. Changing to insulin can actually be a lot better.

Making the Switch to Insulin

Making the transition is much easier than it used to be because most patients are started on a long-acting insulin that does not need to be matched with food intake.

Insulin pens that are preloaded are replacing insulin that needs to be drawn up into a syringe. Patients may still be worried about giving themselves injections, but because the needle is so tiny the adjustment is often quick.

Toujeo and Lantus are long-acting forms of insulin that are available in a prefilled injectable pen.

There’s also a type of rapid-acting insulin, Afrezza, that can be inhaled through the mouth via an inhaler.

And a new class of medication called sodium-glucose cotransporter 2 (SGLT2) inhibitors is also available now, according to Mazhari. “It works via a different pathway that’s not pancreas-dependent, offering another medical therapy option for patients with type 2 diabetes.”

The key to an easy transition to insulin is education.

“Patients need to know how to take their insulin properly since there are many formulations on the market, including short- and long-acting insulin and premixed,” Mazhari said. “Most can be started on a long-acting insulin once a day, though for some patients short-acting or mealtime insulin may be necessary as well. Insulin doses need to be further adjusted depending on blood sugar readings.”

Important Insulin Basics

Dosing and Type Your dosing schedule and insulin type will depend on how advanced your diabetes is, plus your weight, age, level of physical activity, and the diabetic diet you’re on. There’s no “standard dose” for insulin.

Self-Testing Work with your team to come up with a blood sugar testing schedule at home. You may be instructed to check your blood sugar three or four times per day during the adjustment period.

Your healthcare team will use information about your fasting, pre-meal, and post-meal blood sugar levels to make changes to your insulin regimen.

Hypoglycemia Learn the symptoms of low blood sugar, or hypoglycemia, and what to do if you have them. The warning signs include feeling cold, shaky, dizzy, or confused. Symptoms can come on suddenly, so patients should know to drink a half-glass of juice, eat some hard candies, or chew some glucose tabs.

Treatment Team During the transition, stay in close contact with your treatment team. People starting insulin are often advised to meet with their health care providers on a weekly basis until blood sugars stabilize and the appropriate insulin dose is determined.

“The goal of type 2 diabetes treatment is to control blood sugar early, in order to prevent or delay the development of complications and, in those who already have them, to slow or halt their progression, if possible,” said Mazhari.

“The earlier diabetes control is achieved, the better it is for the patient. Unfortunately, in those who already have complications, some of the damage is not reversible,” said Mazhari. “We do our best to control diabetes using the available medications, including insulin, while working with patients to modify their diet and lifestyle.”

“Obesity increases insulin resistance, but more activity and weight loss can lead to better insulin resistance and glucose control. In many cases this can help reduce the number or dose of the diabetic medication the patient is on, including insulin,” Mazhari added.

Understanding A1C

So, what do the numbers mean?

When it comes to the numbers, there’s no one-size-fits-all target. A1C target levels can vary by each person’s age and other factors, and your target may be different from someone else’s. The goal for most adults with diabetes is an A1C that is less than 7%.

A1C test results are reported as a percentage. The higher the percentage, the higher your blood sugar levels over the past two to three months. The A1C test can also be used for diagnosis, based on the following guidelines:

  • If your A1C level is between 5.7 and less than 6.5%, your levels have been in the prediabetes range.
  • If you have an A1C level of 6.5% or higher, your levels were in the diabetes range.

Finally: A1C is also defined as ‘estimated average glucose,’ or eAG

Another term you may come across when finding out your A1C is eAG. Your doctor might report your A1C results as eAG.eAG is similar to what you see when monitoring your blood sugar at home on your meter. However, because you are more likely to check your blood sugar in the morning and before meals, your meter readings will likely be lower than your eAG.

Learn more about A1C and eAG

Learn more about other tests used to diagnose diabetes

What type of diabetes requires insulin injections?

The truth is we all take insulin. Every man, woman, child, chimpanzee, sea otter, and even fish. Insulin is a fundamental element that all critters on the planet share. Insulin the hormone that allows sugar to get from the blood into cells. An analogy that is often given is to picture every cell in your body as a little house with a locked door. Insulin is the key that opens the door so the pizza delivery guy can get it.

So in non-diabetic folks, when the cell orders a pizza the pancreas sends out the delivery guy with a set of keys for the cell’s front door. (Just set aside for the moment the notion of the pizza guy having keys to your house is a more than a little bit creepy.) The delivery guy arrives at the cell’s door step, unlocks the door, and delivers the pizza.

Now in Type-1 Diabetics, like myself, our immune system has killed off all of the cells in the pancreas that make insulin. So we’ve got a pizza chain with no drivers. Quite literally, we die if we do not inject. I guess you could compare injections to the pizza chain resorting to calling up a Temp Service and hiring some drivers for the day.

Type-2 Diabetes is a bit different. Lots and lots and lots of drivers, but they are morons and keep leaving the pizza shop with the wrong keys. They can’t open the doors at the cells, the cells are getting hungry and angry and are calling the pancreas and saying “hey, we ordered a pizza an hour ago and the #@$% driver hasn’t shown up yet!” And the pancreas is like, hey, we sent the guy out… we don’t know what happened, but we’ll send another driver pronto.

What’s happening in T-2s is called insulin resistance. For a time, the body makes lots and lots of insulin, but it just doesn’t work very well. To fight this resistance the body over produces insulin and eventually all of this overwork burns out the pancreas. In fact, as long as the body can keep up, most people are clueless that they have diabetes. It’s been estimated that by the time of diagnosis most T-2s only have about 10% of their insulin production capacity left. By 14 years post-diagnosis, it may be effectively gone. Once it is gone, it needs to be replaced to keep sugar levels safe. And that means injections. Bottom line: most diabetics will eventually need insulin. It is the nature of the disease, not a failure on the part of the person.

Last note: women with gestational diabetes will often be given insulin for the simple fact that as a natural hormone, it is safe for her baby for her to take it.

Insulin Routines

Insulin Routines

  • Insulin is required for people with type 1 diabetes and sometimes necessary for people with type 2 diabetes.
  • Syringe is the most common form of insulin delivery, but there are other options, including insulin pens and pumps.
  • Insulin should be injected in the same general area of the body for consistency, but not the exact same place.
  • Insulin delivery should be timed with meals to effectively process the glucose entering your system.

Insulin therapy

With the help of your health care team, you can find an insulin routine that will keep your blood glucose near normal, help you feel good, and fit your lifestyle.

Type 1

People diagnosed with type 1 diabetes usually start with two injections of insulin per day of two different types of insulin and generally progress to three or four injections per day of insulin of different types. The types of insulin used depend on their blood glucose levels. Studies have shown that three or four injections of insulin a day give the best blood glucose control and can prevent or delay the eye, kidney, and nerve damage caused by diabetes.

Type 2

Most people with type 2 diabetes may need one injection per day without any diabetes pills. Some may need a single injection of insulin in the evening (at supper or bedtime) along with diabetes pills. Sometimes diabetes pills stop working, and people with type 2 diabetes will start with two injections per day of two different types of insulin. They may progress to three or four injections of insulin per day.

Fine-tuning your blood glucose

Many factors affect your blood glucose levels, including the following:

  • What you eat
  • How much and when you exercise
  • Where you inject your insulin
  • When you take your insulin injections
  • Illness
  • Stress

Self monitoring

Checking your blood glucose and looking over results can help you understand how exercise, an exciting event, or different foods affect your blood glucose level. You can use it to predict and avoid low or high blood glucose levels. You can also use this information to make decisions about your insulin dose, food, and activity.

For more information, see our Blood Glucose Control section.

Insulin delivery

Many people who take insulin use a syringe, but there are other options as well.

Insulin pens

Some insulin pens contain a cartridge of insulin that is inserted into the pen and some are pre-filled with insulin and discarded after all the insulin has been used. The insulin dose is dialed on the pen, and the insulin is injected through a needle, much like using a syringe. Cartridges and pre-filled insulin pens only contain one type of insulin. Two injections must be given with an insulin pen if using two types of insulin.

Pump therapy

Insulin pumps help you manage diabetes by delivering insulin 24 hours a day through a catheter placed under the skin. Read more about insulin pumps.

Site rotation

The place on your body where you inject insulin affects your blood glucose level. Insulin enters the blood at different speeds when injected at different sites. Insulin shots work fastest when given in the abdomen. Insulin arrives in the blood a little more slowly from the upper arms and even more slowly from the thighs and buttocks. Injecting insulin in the same general area (for example, your abdomen) will give you the best results from your insulin. This is because the insulin will reach the blood with about the same speed with each insulin shot.

Don’t inject the insulin in exactly the same place each time, but move around the same area. Each mealtime injection of insulin should be given in the same general area for best results. For example, giving your before-breakfast insulin injection in the abdomen and your before-supper insulin injection in the leg each day give more similar blood glucose results. If you inject insulin near the same place each time, hard lumps or extra fatty deposits may develop. Both of these problems are unsightly and make the insulin action less reliable. Ask your health care provider if you aren’t sure where to inject your insulin.


Insulin shots are most effective when you take them so that insulin goes to work when glucose from your food starts to enter your blood. For example, regular insulin works best if you take it 30 minutes before you eat.

Too much insulin or not enough?

High morning blood glucose levels before breakfast can be a puzzle. If you haven’t eaten, why did your blood glucose level go up? There are two common reasons for high before-breakfast blood glucose levels. One relates to hormones that are released in the early part of sleep (called the Dawn Phenomenon). The other is from taking too little insulin in the evening. To see which one is the cause, set your alarm to self-monitor around 2 or 3 a.m. for several nights and discuss the results with your health care provider.

Why Insulin Can Become Necessary for a Person with Type 2 Diabetes

Starting insulin treatment should not be seen as a setback.

People with type 2 diabetes may require insulin when their meal plan, weight loss, exercise and antidiabetic drugs do not achieve targeted blood glucose (sugar) levels.

Diabetes is a progressive disease and the body may require insulin injections to compensate for declining insulin production by the pancreas. That is why starting insulin treatment should never be seen as a failure.

Starting insulin treatment should never be seen as a failure.

Treatment with insulin may be added to an antidiabetic medication or completely replace it. Regardless of the treatment, lifestyle habits (diet, exercise, stress management) are essential to managing diabetes.

Many people are reluctant to inject insulin for various reasons:

  • Fear of pain or needles
  • Guilt
  • Impression that this is the “last resort”
  • Fear of hypoglycemic attacks
  • Fear of weight gain
  • Memories of loved one who had to take insulin

If this is the case, do not hesitate to discuss your concerns with a health care professional. Some of your fears may be due to false beliefs. Learning more about today’s insulin treatment will probably allay your fears. For many people, insulin is an effective way to achieve good blood-sugar control, which can prevent or delay certain diabetes complications over the long term.

Every person with diabetes being treated with insulin should be trained by a health care professional. This training should include the different injection steps, as well as the treatment and prevention of hypoglycemia, which can occur in anyone on insulin.

Research and text: Cynthia Chaput, Dietitian

Scientific review: Louise Tremblay, Nurse. M. Ed.

June 2014 – Revised May 2016

Insulin therapy for type 2 diabetes ‘may do more harm than good’

A new study published in the journal JAMA Internal Medicine suggests that for older patients with type 2 diabetes, medications to lower blood sugar levels may “do more harm than good.”

Approximately 25.8 million people in the US have diabetes, with type 2 diabetes accounting for 90-95% of all cases.

Type 2 diabetes is characterized by insulin resistance – the inability of the body to produce enough insulin or use the hormone effectively, which causes high blood sugar levels. Over time, high blood sugar levels can cause kidney, eye or heart diseases, nerve damage or stroke.

Diagnosis of type 2 diabetes is usually determined through a blood test that measures hemoglobin A1c levels in the blood. This test reveals the average level of glucose the patient has had in their blood over the past 3 months.

In the US, type 2 diabetes is diagnosed when hemoglobin A1c levels reach 6.5% or higher. The higher A1c levels are, the greater the risk of other health problems.

Sometimes the condition can be managed through changes in diet, but other patients with type 2 diabetes may need medication – such as insulin or metformin – to help lower their blood sugar levels, and ultimately, reduce the risk of diabetes complications.

But the researchers of this latest study, from University College London (UCL) in the UK, the University of Michigan Medical School and the Ann Arbor Veterans Affairs Hospital, MI, claim that the benefits of such treatment – particularly for people over the age of 50 – may not always outweigh the negatives.

“In many cases, insulin treatment may not do anything to add to the person’s quality life expectancy,” says study co-author John S. Yudkin, emeritus professor of medicine at UCL. “If people feel that insulin therapy reduces their quality of life by anything more than around 3-4%, this will outweigh any potential benefits gained by treatment in almost anyone with type 2 diabetes over around 50 years old.”

Benefits ‘dependent on age at treatment initiation and side effects’

For their study, led by Sandeep Vijan, professor of internal medicine at the University of Michigan Medical School, the team assessed 5,102 patients in the UK with type 2 diabetes who managed their condition through the use of insulin pills or injections.

Share on PinterestResearchers say that the benefits of insulin therapy for patients with type 2 diabetes are very much dependent on their age at treatment initiation and the potential side effects, rather than their blood sugar levels.

Over a 20-year follow-up, the researchers looked at how the treatments affected patients’ overall quality of life and whether they were effective in reducing their risk of diabetes complications.

They then compared the reduced risk of such complications with the burden of using diabetes medications and the side effects associated with them.

According to the researchers, they found that the benefits of insulin therapy for patients with type 2 diabetes are very much dependent on their age at treatment initiation and the potential side effects, rather than their blood sugar levels.

For example, they estimate that a person with type 2 diabetes who begins insulin therapy at age 45 and lowers their hemoglobin A1c levels by 1% may experience an extra 10 months of healthy life.

But for a patient who starts treatment for type 2 diabetes at age 75, they estimate the therapy may only gain them an additional 3 weeks of healthy life. The researchers say this prompts the question – is 10-15 years of pills or injections with possible side effects worth it?

Prof. Yudkin comments:

“Ultimately, the aim of a treatment is not to lower blood sugar for its own sake but to prevent debilitating or deadly complications. If the risk of these complications is suitably low and the burden of treatment correspondingly high, treatment will do more harm than good. The balance between the two can never be defined by a simple figure like blood sugar level.”

The team says their findings apply to type 2 diabetes patients with hemoglobin A1c levels below 8.5%. But they note that patients with levels above 8.5% may be likely to see greater benefits from insulin therapy, as they are at greater risk of diabetes complications.

However, the team concludes that using a patient’s hemoglobin A1c levels alone to judge whether they will benefit from insulin therapy is a “fundamentally flawed strategy.”

“Instead,” they add, “each glycemic treatment decision should be individualized, mostly on the basis of the patients’ views of the burdens of therapy, with age and initial level of glycemic control important secondary considerations.”

“Currently, we are failing our patients by not recognizing that their preferences and views of treatment burden are the most important factors in helping them make glycemic treatment decisions that are best for them.”

Earlier this year, Medical News Today reported on a study published in the journal PLOS One, in which researchers took to Mount Everest in order to show how hypoxia – low oxygen levels in the body – is associated with development of type 2 diabetes.

When most people find out they have Type 2 diabetes, they are first instructed to make changes in their diet and lifestyle. These changes, which are likely to include routine exercise, more nutritious food choices, and often a lower calorie intake, are crucial to managing diabetes and may successfully lower blood glucose levels to an acceptable level. If they do not, a drug such as glyburide, glipizide, or metformin is often prescribed. But lifestyle changes and oral drugs for Type 2 diabetes are unlikely to be permanent solutions. This is because over time, the pancreas tends to produce less and less insulin until eventually it cannot meet the body’s needs. Ultimately, insulin (injected or infused) is the most effective treatment for Type 2 diabetes.


There are many barriers to starting insulin therapy: Often they are psychological; sometimes they are physical or financial. But if insulin is begun early enough and is used appropriately, people who use it have a marked decrease in complications related to diabetes such as retinopathy (a diabetic eye disease), nephropathy (diabetic kidney disease), and neuropathy (nerve damage). The need for insulin should not be viewed as a personal failure, but rather as a largely inevitable part of the treatment of Type 2 diabetes. This article offers some practical guidance on starting insulin for people with Type 2 diabetes.

When to start insulin

Insulin is usually started when oral medicines (usually no more than two) and lifestyle changes (which should be maintained for life even if oral pills or insulin are later prescribed) have failed to lower a person’s HbA1c level to less than 7%. (HbA1c stands for glycosylated hemoglobin and is a measure of blood glucose control.) However, a recent consensus statement from the American Diabetes Association and the European Association for the Study of Diabetes suggested that insulin is a reasonable choice if a person’s HbA1c level remains above 7% while he is taking metformin alone. (The effects of metformin should be seen within three to four months of starting it.)

— Learn More About Treatment Approaches >>

Large studies of people with Type 2 diabetes have shown that only about 30% of people taking two oral medicines have an HbA1c level of less than 7% after three years. Insulin is usually recommended as the initial therapy for diabetes if a person’s HbA1c level at diagnosis is greater than 10% or if someone’s fasting blood glucose level is consistently above 250 mg/dl.

Studies have shown that many doctors wait until someone’s HbA1c level is higher than 9% to start insulin therapy, which often results in months or years of high blood glucose and an increased risk of developing complications later on. One unfortunate reality is that many busy medical practices are not set up to address the needs of people who take insulin. Starting insulin requires education and easy access to health-care providers who are knowledgeable about insulin therapy, including diabetes nurse educators, pharmacists, and doctors.

Types of insulin

There have been significant innovations in insulin products over the last several years that have made insulin therapy more effective, more accessible, and safer. Before starting insulin, it is helpful to understand its function in the body. Insulin is needed for most cells throughout the body to take in glucose from the blood, which the cells use as fuel. In people without diabetes, the pancreas continuously secretes insulin at a background, or basal, level to provide a stable supply of glucose to the body’s cells and prevent a buildup of glucose in the blood as glucose is steadily released from the liver. In response to eating, the pancreas secretes a larger pulse, or bolus, of insulin. This bolus of insulin allows the liver to store energy from the food for later use instead of releasing it as glucose all at once, stabilizing the blood glucose level.

Injected insulin that functions as basal insulin is called “long-acting” and provides a relatively low level of insulin for a long period. Insulin that functions as bolus insulin is called “short-acting” or “rapid-acting” and provides a higher level of insulin that is used quickly.

Three types of long-acting insulin are commonly used: NPH (brand name Humulin N), insulin glargine (Lantus), and insulin detemir (Levemir). NPH insulin lasts 10–16 hours in the body. It may initially be taken as a single daily injection, but eventually it usually needs to be taken twice a day. The main advantage of NPH insulin is that it is inexpensive. Its main drawback is that the timing of its peak of action is unpredictable, which can lead to hypoglycemia (low blood glucose) if meals are not timed with injections properly. (An insulin’s “peak” is when it is most active in the body. It varies by type of insulin, and ideally injections are timed so that the insulin’s peak coincides with the rise in blood glucose that follows a meal.)

Insulin glargine is a long-acting insulin that can last up to 24 hours and has little peak in its action, which reduces the risk of hypoglycemia. Another advantage of insulin glargine is that it only requires one injection each day for the vast majority of people with Type 2 diabetes.

The newest long-acting insulin, insulin detemir, usually lasts 16–20 hours. In general, it has less of a peak than NPH but is not as “flat” as glargine. Insulin detemir tends to be the most predictable of the long-acting insulins. It has also consistently been shown to cause less weight gain than the other insulins (or even mild weight loss). Detemir and glargine cost about the same, but both are more expensive than NPH. They cannot be mixed with other insulins in the same syringe, while NPH can. All three basal insulins are available in prefilled pens that do not require syringes or vials. Doses of insulin can be dialed into the pen, and the pens can be carried conveniently in a coat pocket, purse, or knapsack.

The oldest type of short-acting insulin is Regular insulin (brand names Humulin R and Novolin R). It lasts about 6–8 hours and has its peak about 2 hours after injection. It does not start working (lowering blood glucose) until about 30–60 minutes after injection, so it can be difficult to coordinate the timing of injections with meals. For example, if you take an injection of Regular insulin right before you eat lunch, your lunch will likely raise your blood glucose level before your insulin starts working to lower it. You would need to inject the insulin 30–60 minutes before eating lunch to match the rise in blood glucose with the action of the insulin. In spite of this inconvenience, Regular insulin is still widely used because it is very inexpensive, and because many physicians have years of experience prescribing it.

Three other forms of short-acting insulin (considered “rapid-acting”) are insulin aspart (NovoLog), insulin lispro (Humalog), and insulin glulisine (Apidra). These insulins each have a slightly different chemical structure, but all last less than 5 hours and start to work within 15 minutes. They are all relatively expensive but are easier to coordinate with meals than Regular insulin. In general, these three rapid-acting insulins match up better with the body’s release of glucose into the blood after eating, resulting in a lower risk of hypoglycemia, but are no better than Regular insulin at lowering the HbA1c level. All short-acting insulins are available in easy-to-use insulin pens.

Long- and short-acting insulins are also available in premixed combinations such as 70% NPH and 30% Regular, also known as “70/30.” Although premixes may initially appear to be more convenient, they are difficult to tailor to individual needs due to the fixed proportions of the combinations. A person who needs, for example, more short-acting insulin but not more long-acting insulin is out of luck when using a premix. For more information on the different types of insulin, see “Insulin Action times.”

How to start insulin

When first prescribing insulin for a person with Type 2 diabetes, doctors generally start with a single daily injection of long-acting insulin. Determining what dose of insulin to begin with can be done in different ways. One option is to choose a starting dose based on a person’s weight. Eventually, many people with Type 2 diabetes will require 1–2 units of insulin for every kilogram of body weight; that is, an 80-kilogram (175-pound) person will require at least 80 units of insulin each day. To start, however, your doctor may begin by prescribing 0.15 units of insulin per kilogram. For an 80-kilogram person, this would be 12 units.

Another option is simply to start with 10 units of insulin, a large enough dose to decrease blood glucose levels for most people but not so large that it is likely to cause hypoglycemia. The dose can then be increased every 3–7 days based on fasting blood glucose values. A morning blood glucose reading of 80–100 mg/dl is ideal, so with numbers that fall in this range, you would not make any changes. If your morning blood glucose readings were under 80 mg/dl, you would decrease your insulin dose by 2 units. Most people, however, will need to increase their dose of insulin above the initial level. It is generally safe to adjust one’s basal insulin according to this scale.

Most doctors initially recommend taking insulin in the evening, since this helps reduce a person’s fasting blood glucose level the next morning. However, one problem with taking NPH insulin at bedtime is that it often peaks in the middle of the night, increasing the possibility of hypoglycemia during sleep. Since insulin glargine and insulin detemir do not have a significant peak of action, it is safer to take one of these at bedtime. Depending on a person’s blood glucose trends or personal preferences, basal insulin can also be taken in the morning instead of at bedtime.

One common error made by doctors is to focus too much on normalizing the fasting morning blood glucose level without considering the importance of the bedtime blood glucose level. For example, a person might take 40 units of insulin glargine at bedtime and have an optimal fasting blood glucose level of 110 mg/dl in the morning. However, this person could have a bedtime blood glucose level in the 300’s, which indicates the need to take insulin at dinner (often called “covering” the meal). So although his fasting blood glucose level is fine, this person will still have an HbA1c level greater than 9%. This is why it is important not to rely only on fasting blood glucose levels, but to also use the HbA1c level and, if necessary, blood glucose readings throughout the day to guide treatment.

If after three months of using long-acting insulin alone the HbA1c level is still above 7%, then using Regular or rapid-acting insulin to cover meals will be necessary. Mealtime insulin can initially be given at the largest meal of the day, which is dinner for most Americans. A simple approach for starting mealtime insulin is to decrease the long-acting insulin dose by 10% and take the difference as rapid-acting insulin at dinnertime. For example, if you previously took 20 units of glargine at bedtime, you would take 2 units of aspart, lispro, or glulisine at dinner and 18 units of glargine before bed.

An important concept in insulin therapy is taking “correction doses” of insulin. This means taking extra rapid-acting insulin before a meal to correct for high blood glucose. A common correction dose is 2 extra units of insulin for a premeal blood glucose level above 150 mg/dl; even more will be needed if the level is above 200. Although there is a large range of appropriate correction doses, here is an example of a typical scale. Correction doses can significantly impact blood glucose levels. For example, if you generally take 6 units of insulin aspart with lunch but your blood glucose level before lunch is 250 mg/dl, your usual 6 units will not adequately lower both the current high blood glucose and the anticipated rise from lunch. If you take 4 additional units of insulin, the correction dose will cover your premeal high glucose and the 6 units will cover your meal. Although this system can take a few weeks to adjust to, most people find it rewarding because they can take action to lower their high blood glucose as soon as they know about it, rather than letting it remain high throughout the day.

Insulin and weight gain

When first starting insulin therapy, many people complain that they are eating and exercising the same amount as before but gaining weight. This occurs because with insulin, the body is able to use glucose that was previously wasted in the urine. Glucose that is not needed right away for energy is stored as fat. Studies have shown that weight gain may lead people, particularly women, to not follow their prescribed insulin regimen. This is a dangerous practice that can lead to sustained high blood glucose and a higher risk of long-term complications. Weight gain with insulin therapy is not inevitable, but avoiding it or reversing it generally requires eating fewer calories and/or exercising more.

Continuing oral medicines

Many people ask whether it is worthwhile to continue their oral medicines once they have started insulin. Many studies have shown that people who use both an oral drug and insulin have better blood glucose control than those taking long-acting insulin alone. Continuing metformin when beginning insulin, for example, can reduce the weight gain that often occurs in the first year of insulin therapy. Sulfonylurea drugs such as glyburide and glipizide can help reduce high blood glucose after meals and are effective when combined with a single injection of long-acting insulin.

Metformin can be continued even when short-acting insulin with meals is introduced. Glyburide and glipizide are generally discontinued when short-acting insulin is begun.

Thiazolidinedione drugs such as pioglitazone (Actos) are associated with weight gain and fluid retention when combined with insulin, so they are usually discontinued when insulin therapy is initiated.

Another medicine that is commonly used prior to starting insulin is exenatide (Byetta). This injectable drug is associated with significant weight loss, and many doctors opt to continue exenatide when starting basal insulin. However, it must be emphasized that at this time, exenatide is only approved by the US Food and Drug Administration for use along with insulin glargine.

Back to basics

The overall goal in treating diabetes is to maintain optimal blood glucose levels to reduce the risk of diabetic complications. For many people, insulin is the best way to achieve this goal. There is no single right way to begin insulin; a regimen should take individual needs and circumstances into account. Insulin doses and regimens are also likely to change over time as people’s lives – and bodies – change. With just a little bit of knowledge, however, you can begin insulin therapy undaunted and ready to take the next step in controlling your diabetes.

Want to learn more about insulin? Read “What Does Insulin Do?” “Types of Insulin,” “Everything You Ever Wanted to Know About Injecting Insulin,” “Getting Down to Basals,” and “Selecting an Insulin Program for Type 1 Diabetes.”

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