Why does diabetes cause thirst?

Q. My father was a Type 2 diabetic. I am 39, not overweight, don’t smoke and am basically healthy. But I get extremely thirsty after I drink a lot (12 ounces). I’m fine until I have to urinate, then my mouth dries up as if all the moisture in my body is gone. I don’t understand why I feel so dehydrated when I should feel rehydrated.

I mentioned this to a diabetic person I know, and she says it sounds like diabetes. I am concerned because it used to happen only once in a while, but now it is happening almost daily. Do you think I should be tested for diabetes or could it be something else?


A. The quick answers to your questions are yes, you definitely should be tested for diabetes, and yes, it could be something else. Let me explain.

Diabetes mellitus (the more common form of diabetes) is an endocrine disorder in which blood levels of glucose (a form of sugar) are abnormally high because insulin is not released or used properly. Insulin is a hormone released from the pancreas and is responsible for maintaining appropriate blood-sugar levels.

There are two types of diabetes mellitus, Type 1 and Type 2. In Type 1 diabetes, also called insulin-dependent diabetes, the pancreas produces little or no insulin.

In Type 2 diabetes, which your father had, the pancreas usually produces insulin, but the body cannot use the insulin effectively. The end result is an unhealthy buildup of glucose in the blood and an inability of the body to make efficient use of its main source of fuel. This type of diabetes is often seen in families.

Your diabetic friend was on the right track; early symptoms of Type 2 diabetes include abnormal urination and thirst. When blood sugar levels in the blood become abnormally high, some glucose overflows into the urine, “dragging” more water with it.

The kidneys produce additional water in the urine to dilute the glucose, resulting in increased volumes of urine and more frequent urination (polyuria). This urination creates abnormal thirst (polydipsia).

In Type 2 diabetes, the increased urination and thirst are mild initially, then gradually get worse after weeks or months. This does sound like the symptoms you describe.

Other symptoms you should be on the lookout for include excessive hunger, blurred vision, drowsiness, nausea and decreased endurance.

A convenient and relatively accurate test for “overflow” sugar in the urine are the dipstick tests. You may want to try this test first. Check with your pharmacist about the right one for you and be sure to follow directions.

My advice, though, is to have the more accurate test that checks the blood (actually the serum part of the blood) for high levels of sugar. If blood taken after fasting has a plasma glucose level of more than 126 milligrams per deciliter, a measured dose of glucose is given orally and blood is tested at intervals after that. Obviously, this is done by a health-care professional.

Excessive thirst also can be caused by diabetes insipidus, which is an endocrine disorder unrelated to diabetes mellitus; hyperthyroidism; and some mental health problems. Occasional excessive thirst can be the result of dry mouth caused by a variety of other problems.

Write to Allen Douma in care of the Chicago Tribune Health & Family section, 435 N. Michigan, Chicago, IL 60611; or contact him at [email protected] This column is not intended to take the place of consultation with a health-care provider.

Feeling thirsty and diabetes

Why does diabetes make you thirsty?

The part of our brain that tells us we are thirsty is called the hypothalamus. Both the brain and kidneys can signal the adaptive ‘thirst’ response telling us we are thirsty. Paying attention to excessive thirst is important because it could be one of the warning signs of diabetes.

Excessive thirst & hyperglycemia

Two of the most common symptoms associated with diabetes (type 1 & type 2) are increased thirst and increased urine production. The kidneys are a common factor between these two symptoms. Excessive thirst may be a symptom of high blood sugar (hyperglycemia). It’s important to be able to recognize any imbalance in thirst or urine production.

It’s the function of the kidneys and other organs to help filter out impurities. When there is a buildup of sugar in the bloodstream, our organs, especially the kidneys may become ‘overworked.’ Excess sugar becomes a burden directly on the kidneys as they work to keep up with the volume of excess sugar. The impact of excess blood sugar causes a reaction of hydration which notifies our brain that more fluids are needed causing extreme thirst.

Early detection prevents organ damage

Not only the kidneys but over time if diabetes goes undiagnosed or untreated the pancreas can also be permanently damaged. If you are noticing extreme thirst, talk with your healthcare provider. There are tests that can be done to determine its cause. Recognizing symptoms like extreme thirst and urine production and getting tested for diabetes, can help prevent organ damage.

Typical symptoms of diabetes include:

  • Urinating often
  • Feeling very thirsty
  • Feeling very hungry – even though you are eating
  • Extreme fatigue
  • Blurry vision
  • Cuts/bruises that are slow to heal
  • Weight loss – even though you are eating more (type 1)
  • Tingling, pain, or numbness in the hands/feet (type 2)

To learn more about diabetes talk with your healthcare provider and visit Michigan State University Extension.

Excessive thirst, frequent urination and increased urine production

Excessive thirst (polydipsia), frequent urination (more than eight times per day), and increased urine production (polyuria) (generally considered urine output of over 3 liters per day) are classic symptoms of diabetes mellitus, resulting from the effects of “>high blood glucose. They are also symptoms of a dangerous complication of diabetes called diabetic ketoacidosis. To understand the cause of these symptoms, it’s necessary to understand a little about the role and function of the kidneys. The role of the kidneys is to filter waste out of the blood and maintaining a balance of chemical elements in the blood. The waste products that the kidney removes from the blood are sent to the bladder, which produces urine, which in turn is passed out of the body.1,2

Learn more about diabetic ketoacidosis.

The dangers of ongoing kidney strain

Uncontrolled diabetes with high levels of blood glucose can place a great deal of stress on kidney function and over time and can ultimately cause kidney disease (also called nephropathy). Excessive thirst, frequent urination, and increased urine production are signs that the kidney is working overtime to filter high levels of glucose out of the blood. To accomplish this, the kidneys produce a high volume of urine, which results in an increase in the frequency of urination and the need to urinate at night (this is called nocturne).1

Because of extra urine production, the body becomes easily dehydrated, resulting in excessive thirst. Often, an individual who experiences excessive thirst will consume carbonated drinks containing sugar to satisfy this thirst, a choice that results in a worsening of symptoms. Despite the efforts of the kidney to meet extra demands of filtering glucose out of the blood, over time high blood glucose damages the very filtering mechanism that allows the kidney to carry out its job. This is why uncontrolled diabetes is often associated with a decrease or loss of kidney function.1

Symptoms in older people

As a person ages, the capacity of their kidney to absorb excess glucose increases. Therefore, in an older person, the symptoms of thirst, increased frequency of urination, and increased volume of urine may only become apparent with higher blood glucose levels. In fact, as a person ages, the threshold for experiencing sensation of thirst increases. This means that an older person with high blood glucose is at higher risk for becoming dehydrated than a younger person and at higher risk of developing hyperosmolar syndrome.3

Learn more about hyperosmolar syndrome.

What should I do if I experience these symptoms?

If you experience these classic symptoms of diabetes and you have not been diagnosed with diabetes, you should see your doctor and discuss your symptoms. Your doctor will evaluate you and identify the cause of these symptoms. As part of this evaluation, your doctor will measure your blood glucose to determine if it is high and whether you may have diabetes. If you have already been diagnosed with diabetes, these symptoms are signs that your blood glucose is out of control. Your doctor will work with you to help you control your blood glucose, using lifestyle modifications, including a healthy, calorie-appropriate eating plan, regular physical activity, and weight loss, and, if these modifications are not enough, medication.

Learn more about medications that I can use to help control my blood glucose.

Polydipsia is the term given to excessive thirst and is one of the initial symptoms of diabetes. It is also usually accompanied by temporary or prolonged dryness of the mouth

We all get thirsty at various times during the day. Adequate daily intake of water (several glasses) is very important as water is essential for many bodily functions, including regulating body temperature and removing waste.

However, if you feel thirsty all the time or your thirst is stronger than usual and continues even after you drink, it can be a sign that not all is well inside your body.

Causes of polydipsia

Increased thirst is often the reaction to fluid loss during exercise, or to eating salty or spicy foods. It can also be caused by:

  • Diarrhoea
  • Vomiting
  • Profuse sweating
  • Significant blood loss or
  • Certain prescription medications

Increased thirst can also occur as a result of high blood sugar levels in people with diabetes or yet to be diagnosed diabetes.

Persistent excessive thirst can be the result of one of the following:

  • Diabetes mellitus
  • Diabetes insipidus – a condition unrelated to diabetes mellitus that affects the kidneys and the hormones that interact with them, resulting in large quantities of urine being produced
  • Dehydration
  • Loss of body fluids from the bloodstream into the tissues due to: burns or severe infections (sepsis) or heart, liver, or kidney failure
  • Psychogenic polydipsia – compulsive water drinking associated with mental/psychiatric disorders

Excessive thirst can be caused by high blood sugar (hyperglycemia), and is also one of the ‘Big 3’ signs of diabetes mellitus

Increased thirst and diabetes

Increased thirst in people with diabetes can sometimes be, but certainly not always, an indication of higher than normal blood glucose levels

People with diabetes with access to blood glucose testing equipment may wish to test their blood sugar levels when they are thirsty to determine whether their blood sugar levels are going too high.

If you do not have blood glucose testing equipment and are experiencing regular thirst which you think may be connected with your diabetes, speak with your health team who should be able to advise you.

Recognising symptoms of polydipsia

As anyone and everyone will have experienced the sensation of feeling thirsty, it is very important not to jump to conclusions.

However, the symptoms of polydipsia are recognised as:

  • Having persistent and unexplained thirst, regardless of how much you drink
  • Passing more than 5 litres of urine a day

When to see your doctor

If you have diabetes and experience increased thirst for a number of days, you should make an appointment to see your doctor/healthcare team

If you don’t have diabetes, you should see a doctor if the reason for thirst cannot be explained and particularly if you have other symptoms of diabetes – in paticular polyuria and polyphagia

Why Does Diabetes Cause Excessive Thirst?

We’ve written before about the signs and symptoms of diabetes. While there are a lot of sources about what symptoms diabetes causes, and even some good information about why they’re bad for you, what you don’t often get are the “whys”. And while the “whys” aren’t necessarily critical for your long-term health, they can help you to understand what’s going on with your body and why it acts the way it does. That, in turn, can help with acceptance and understanding of how to better treat the symptoms, which in turn can help you stay on a good diabetes management regimen. In short, you don’t NEED to know why diabetes causes excessive thirst, but knowing the mechanism behind it can make your blood glucose control regimen make more sense and help you stick to it.

So why DOES diabetes cause thirst? First, we’d like to start by saying that excessive thirst is not a good indicator of diabetes. For many people, the symptom creeps up so slowly that it’s almost impossible to determine if your thirst has noticeably increased (unless you keep a spreadsheet of how much water you drink, in which case you also probably get tested pretty regularly anyway). It’s also a common enough symptom that a sudden increase in thirst can mean almost anything. Some conditions that cause thirst increases include allergies, the flu, the common cold, almost anything that causes a fever, and dehydration caused by vomiting or diarrhea. So while excessive thirst is one of those diabetes symptoms that happens, and needs to be addressed, it’s not always a great sign that you should immediately go out and get an A1C test.

Why does diabetes cause thirst?

Excessive thirst, when linked to another condition as a symptom or comorbidity, is called polydipsia. It’s usually one of the earliest symptoms of diabetes to develop, and is often accompanied by excessive dryness of the mouth (“cotton mouth”). In most people with Type 1 or Type 2 diabetes, the thirst builds slowly enough that it is often incredibly difficult to notice until other symptoms present themselves or until the point of major dehydration.

When glucose becomes hyper-concentrated in your bloodstream, usually about 200mg/dL – though this number varies from person to person, your kidney loses the ability to reuptake (pull out) glucose from water. Under normal circumstances, almost all glucose is pulled out of urine and back into the body (as is most of the water, though this depends on how hydrated you are). Since the body can no longer pull glucose out from water in your kidneys, the osmotic pressure (the pressure that builds between a liquid with a high concentration of of solutes and a liquid with a low concentration) builds up. Eventually, it gets so high that water can no longer be absorbed back into your bloodstream, and is in fact being absorbed OUT of your bloodstream.

Side-effects of Type 1 diabetes dehydration

Increased thirst, itself, might seem like a minor problem. The underlying dehydration that causes it, however, is incredibly serious. Immediate effects of not treating severe diabetes-related dehydration can include headaches, nausea, dizziness, and fainting.

For people with diabetes, dehydration can also cause diabetic ketoacidosis. DKA is a condition that causes naturally-occurring acids to build up in the body and can lead to coma, organ failure, or even death.

Even more problematic, severe dehydration actually causes blood sugar levels to rise faster than normal. Part of the reason for this is that the kidneys slowly begin to produce less urine than usual in the presence of prolonged dehydration, and so won’t be able to expel as much excess glucose. A less well-known reason is that dehydration causes the body to release adrenaline and other hormones that act as insulin blockers. For those with Type 2 diabetes, the effect is as if their diabetes had suddenly kicked into overdrive, and glucose stops being broken down almost completely.

If you notice any prolonged symptoms of dehydration, you should immediately schedule an appointment with your physician. If the symptoms include lack of consciousness, shock, or severe impairment, please contact an emergency paramedic team immediately.

Even if you don’t have symptoms of dehydration, drinking plenty of water is an important part of managing a healthy blood glucose level, and staying healthy in general. Bottoms up!

Timesulin Blog

Polydipsia, or Excessive Thirst, as a Sign of Diabetes

Is being thirsty a sign of diabetes? Type 1 diabetes is an autoimmune disease that causes your pancreas to stop producing insulin, a hormone that is essential to getting energy from food. The disease strikes people of all ages and is unrelated to diet or lifestyle. People living with this disease must regularly monitor their blood-sugar levels, inject or infuse insulin, and carefully regulate doses with eating and activity throughout the day.

What is type 1 diabetes?

Approximately 1.25 million Americans live with type 1 diabetes. There is no way to prevent type 1 diabetes, and there’s presently no cure.

Is polydipsia dangerous?

When it comes to diabetes and thirst, polydipsia can be dangerous. The problem is the prolonged dehydration that can lead to nausea, dizziness, headaches and fainting. And if you do have diabetes, but have not yet been diagnosed, this dehydration has the potential to lead to diabetic ketoacidosis which can lead to organ failure, coma or death. Another concern is that extreme dehydration can also make your blood-sugar levels rise more quickly than normal since less urine—and glucose—is being expelled.

What should you do next?

If you think that you may be experiencing diabetes mellitus polydipsia, it’s important that you see a doctor as soon as possible. Regardless of the cause excessive, unexplainable thirst is a sign that something is not right in your body. So make that appointment today.

Polydipsia: Why am I always thirsty?

Some factors that may cause a person to feel more thirsty than usual include:

  • high blood sugar levels due to diabetes mellitus
  • diabetic ketoacidosis (DKA), a complication of hyperglycemia due to diabetes mellitus
  • low vasopressin levels as a result of diabetes insipidus, a rare condition
  • dehydration
  • a loss of bodily fluids, for example, through sweating, diarrhea, or vomiting
  • the use of certain medications
  • having an uncomfortably dry mouth

Polydipsia is a common symptom of high blood sugar levels. It can be an early sign of type 1 diabetes or can indicate that a person with diabetes is having difficulty managing their condition.

Diabetes mellitus

Insulin helps glucose enter the cells, which use it for energy. In a person with diabetes mellitus, the body either does not produce insulin or is not able to use it effectively.

As a result, glucose from food remains in the blood instead of entering the cells, and this leads to disruption in the body.

The kidneys have to work harder to filter the unwanted sugar out of the blood. As the body excretes the sugar into the urine, it takes fluid with it. This loss of fluid causes the person to feel thirsty, so they drink and urinate more.

Common symptoms of high blood sugar levels include:

  • polydipsia
  • polyuria
  • extreme hunger
  • blurred vision
  • fatigue and lack of energy
  • unexplained weight loss or gain

The person may start to notice that they are more prone to infections and that it takes longer for wounds to heal. In time, further complications can arise, such as high blood pressure and cardiovascular disease.

What are the features of type 1 and type 2 diabetes? Learn more here.

Diabetic ketoacidosis (DKA)

Share on PinterestIf a person with diabetes starts to feel more thirsty than usual, they should check their blood sugar levels.

When a person has diabetes and glucose cannot enter the cells to provide energy, the body may start to break down fat for this purpose.

This process produces a toxic byproduct called ketones. If ketones build up in the blood, they can cause it to become too acidic. This change in pH can lead to DKA, which can potentially be fatal.

The early symptoms of DKA are extreme thirst and a frequent need to urinate. A person who has these symptoms should test their blood sugar levels. If these are at 240 milligrams per deciliter or above, the person should check their urine for ketones.

Later symptoms may include

  • a fruity or “acetone” smell on the breath
  • tiredness
  • dry or flushed skin
  • difficulty concentrating
  • confusion
  • difficulty breathing
  • nausea and vomiting
  • abdominal pain
  • loss of consciousness
  • coma

Anyone who has these symptoms should seek emergency medical help as the condition can rapidly become severe and even life-threatening.

Kits for testing ketone levels and blood sugar levels are available for purchase online.

Diabetes insipidus

This form of diabetes is a rare condition that affects one in 25,000 people. It is different from diabetes mellitus, and it does not involve a problem with insulin.

There are different types of diabetes insipidus, each with a different cause. However, they all involve a problem with vasopressin, an antidiuretic hormone that helps control fluid removal through the kidneys.

A person with diabetes insipidus may pass large volumes of clear, odorless urine. According to the National Institute of Diabetes and Digestive and Kidney Diseases, they may pass between 3 and 20 quarts (about 3.4–22.7 L) of urine a day.

These individuals may report polydipsia. Rarely, severe dehydration can also occur.

Dehydration symptoms include:

  • thirst
  • dry skin or eyes
  • tiredness
  • nausea

Even if a person does not think that they are dehydrated, they should seek immediate medical help if they experience the following symptoms:

  • sluggishness
  • dizziness
  • confusion

about diabetes insipidus.

Mental health conditions

In a 2013 study, researchers looked at excessive thirst or liquid consumption in people attending an outpatient clinic for mental health conditions.

Of these people, 15.7% had primary polydipsia, an excessive thirst that is not due to the use of medication or another identifiable cause. In this subgroup, 13 people had schizophrenia, and one person had bipolar disorder.

Medications that doctors prescribe for these and other conditions can also increase thirst.

Reasons that the participants gave for drinking a lot included having a dry mouth, believing that drinking water keeps the body clean, doing it out of habit, and trying to cope with feeling empty.

The authors of a 2017 study concluded that polydipsia had features in common with obsessive-compulsive disorder (OCD). For example, the person is often not aware that their fluid consumption is excessive.

The researchers suggested that there may be a neurobiological link between these conditions and proposed a traumatic brain injury as one possible cause of polydipsia.

When the cause of drinking too much is psychological, there is a risk of water intoxication, which can be dangerous. Researchers do not yet know precisely why polydipsia happens. Scientists have called for further studies to find out more.

Why Do You Get Thirsty When You Have Diabetes?

What is Diabetes?

Diabetes is defined as a chronic health condition in which blood sugar or blood glucose levels become high. There are 2 kinds of diabetes namely Type 1 diabetes and Type 2 diabetes. Diabetes occurs as a result of insulin resistance, obesity, hereditary factors etc. Common symptoms of Diabetes are sudden and unexpected weight loss, blurred vision, increased appetite, numbness and tingling sensation in the feet and hands, fatigue, hard-to-heal sores and increased urination. Another very common symptom of diabetes is excessive thirst felt by the patients. So why does high blood sugar cause increased thirst? Well, first and foremost it should be remembered that excessive thirst is not a favourable indicator of diabetes. For most people this symptom shows up very slowly, which makes it almost impossible to determine any marked increase in the thirst experienced by the individual. Sudden increase in thirst is also a common symptom for many other illnesses like common cold, flu, allergies, other forms of fever, vomiting and diarrhea. So, although heightened thirst does occur in diabetes patients and needs to be treated too, it’s not always a very solid indicator of diabetes. Getting a blood sugar test done is the best way of getting diabetes diagnosed. Are you a high blood sugar patient? Do you feel unusually thirsty? Want to know why do you get so thirsty when you have diabetes? The following read tells all about excessive thirst in diabetes.


Excessive thirst that appears as a symptom of another health condition is termed as Polydipsia. Polydipsia is one of the initial symptoms of diabetes and is generally accompanied by cotton mouth, i.e. increased dryness of the mouth. Although this symptom appears quite early in Type 1 or Type 2 diabetics, it is generally quite difficult to mark. This is because the thirst builds up very slowly and doesn’t get noticed until other symptoms of diabetes present themselves too or until extreme dehydration is experienced by the individual.

Under normal health conditions, when a person is optimally hydrated, almost all the glucose is extracted from their urine by their kidney and returned into the body. But the kidney loses its ability to absorb glucose from water when the glucose in the blood stream becomes hyper-concentrated, i.e. around 200mg/dL for most people. When this occurs, the osmotic pressure increases. Osmotic pressure is defined as the pressure, which is created between liquids with high and low concentration of solutes. The osmotic pressure eventually becomes so high that water can no longer be pulled out and returned back into the blood stream and in fact gets absorbed outside the bloodstream. Thus, diabetics end up urinating more than normal and end up feeling thirstier.

Side-Effects of Type 1 Diabetes Dehydration


Although increased thirst seems like a small health issue, the underlying dehydration that triggers this thirst is considerably serious. If this diabetes related dehydration is not treated in time, side effects like dizziness, nausea, headache and fainting can be experienced by the patient.

Dehydration can also lead to diabetic ketoacidosis or DKA in diabetes patients. DKA is a condition which causes naturally-occurring acids to accumulate in the body and lead to, organ failure, coma and even death.

Further, severe dehydration can actually cause blood sugar levels to rise more rapidly than normal. This happens partially because the kidneys, in the presence of long lasting dehydration, slowly begin to produce less urine than usual and thus are unable to expel much of the excess glucose. A lesser known reason for the elevation in blood sugar levels is that dehydration triggers the body to release adrenaline and other hormones, which act as insulin blockers. For ones with Type 2 diabetes, the effect is as if their diabetes had suddenly kicked into over drive, and glucose stops being broken down almost completely.



If prolonged symptoms of dehydration are experienced, one should immediately consult their doctor. If these symptoms are accompanied by shock, unconsciousness or severe impairment, then one should contact an emergency paramedic team right away. Even if an individual does not display symptoms of dehydration, drinking plenty of water is very essential for managing a healthy blood glucose level in the body and staying fit in general and especially for diabetics. A good understanding and acceptance of the symptoms of diabetes can help a diabetic manage their illness better.

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