How Untreated Diabetes Affects Your Body

Untreated diabetes can lead to long-term complications, including blindness, kidney failure, and nerve damage. Diabetes occurs when your blood sugar levels are too high (hyperglycemia).

Untreated diabetes often occurs because a person doesn't know they have diabetes. The Centers for Disease Control and Prevention (CDC) estimates that 7.2 million Americans have undiagnosed diabetes.

Sometimes people who have diabetes do not take steps to treat it. Symptoms of high blood sugar are often subtle and easy to miss. If you don't test your blood sugar regularly, it may be high, and you don't know it. However, diabetes testing supplies can be expensive, and insurance may not always cover them.

This article discusses the signs of untreated diabetes. It also discusses how untreated diabetes can lead to long-term complications.

woman touching painful leg

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Signs of Untreated Diabetes

High Blood Sugar Level

One of the signs of untreated diabetes is high blood sugar. When you visit your healthcare provider, they will measure your blood sugar and let you know what range your blood glucose should fall in. Healthy blood sugar levels are usually between 70 and 130 mg/dL before meals and below 180 mg/dl two hours after meals. 

High blood sugar is also often associated with a number of symptoms. If you notice any of the following symptoms, contact your healthcare provider right away about getting your blood glucose checked:

  • Increased thirst or hunger
  • Blurred vision
  • Frequent urination
  • Headaches
  • Fatigue
  • Weight loss
  • Skin infections
  • Slow-healing cuts and sores

If your healthcare provider suspects that you have diabetes or prediabetes (a precursor of type 2 diabetes), they will order other tests to confirm the diagnosis.

Frequent Urination

Another common symptom of untreated diabetes is increased urination (polyuria). A person is diagnosed with polyuria when they urinate a minimum of 3 L daily. It is different from urinary frequency, which is the number of times someone pees in a day. In people with diabetes, polyuria is often associated with excessive thirst.

Frequent urination usually happens when your body is trying to clear your blood of excess sugar. Normally, when your kidneys create urine, they reabsorb all of the sugar and direct it back to the bloodstream. With diabetes, excess glucose ends up in the urine, where it pulls more water and results in more urine.

Excessive Thirst

Polydipsia, an excessive form of thirst, is commonly found in people with diabetes. When you have diabetes, your kidneys have to work harder to filter and absorb the excess glucose in your blood. When your kidneys can’t keep up, the excess glucose is excreted into your urine, pulling along fluids from your tissues, which makes you dehydrated. This will usually leave you feeling thirsty.

Blurred Vision

High blood sugar levels in uncontrolled diabetes can damage small blood vessels, including those in your eyes. This can affect the blood vessels connected to the retina, a layer of tissue at the back of your eyeball that is responsible for eyesight, resulting in blurred vision.

Also, fluid can move in and out of the eye as a result of excessive blood glucose, causing swelling of the lens, a part of your eye that bends light and focuses it onto the retina to help you see clearly. As the shape of the lens changes, it distorts the way light is focused onto the retina, and blurriness occurs.


Fatigue is a common symptom among people with diabetes. In this condition, cells in your body cannot use the glucose from the food you ate. Fatigue and weakness can occur as a result.

Poor Wound Healing 

High blood sugar affects the functioning of white blood cells, which are cells in the immune system that fight bacteria and viruses. When white blood cells can’t function properly, the body isn’t able to ward off these foreign threats or heal wounds properly. 

People with untreated diabetes may also not have good blood circulation, which can prevent the body from supplying nutrients to wounds to help them heal.

What’s the Difference Between Untreated Type 1 Diabetes and Untreated Type 2 Diabetes?

Type 1 diabetes is when your pancreas doesn’t produce any insulin at all. If left untreated, it can cause atherosclerosis (narrowing of blood vessels), heart disease, stroke, and eye and kidney diseases.

On the other hand, type 2 diabetes occurs when your pancreas doesn’t produce enough insulin or your body cannot use insulin effectively. Uncontrolled type 2 diabetes can lead to vision loss, kidney failure, and lower limb amputation.


Untreated diabetes will eventually lead to serious complications, including:

  • Heart disease: People living with diabetes are more likely to develop heart problems and even stroke than those without diabetes. 
  • Kidney failure: The kidneys contain large clusters of tiny blood vessels called the glomeruli, which propel the kidneys’ filtering function. Unfortunately, diabetes can damage this filtering system, which may lead to kidney failure.
  • Vision loss: One of the common complications of type 1 and type 2 diabetes is vision loss. Diabetes may attack the blood vessels of the retina. Also, other serious vision complications like cataracts and glaucoma may arise.
  • Nerve damage: Almost half of all diabetic people suffer from nerve damage, also called neuropathy. Large blood sugar deposits damage capillary walls that nurture your nerves, especially in your legs. This may lead to numbness from your toes and up. You may lose your sense of feeling in the affected area. 
  • Infections: High sugar levels can cause dry skin in people with diabetes, and this makes it hard to fight off bacterial and fungal infections. Avoid scratching your skin, especially your legs, by applying moisturizers so that you don’t open sores that lead to skin infections. 
  • Foot problems: Diabetes, which may cause nerve damage to the feet, change in the shape of your feet, or poor blood flow to the feet, may increase the chances of different foot complications. If left untreated, it may lead to serious infections that may require an amputation. 
  • Cognitive problems: Diabetes has been linked to cognitive problems and changes in the brain. Type 2 diabetes is linked to an increased risk of Alzheimer’s disease.

Why Is Alzheimer’s Disease Called Type 3 Diabetes?

“Type 3 diabetes” is a term that has been proposed to describe the connection between Alzheimer’s and diabetes. A variant of a gene, APOE4, that has been associated with Alzheimer’s disease seems to interfere with brain cells’ ability to use insulin, which may eventually cause the cells to starve and die.

Can Complications Be Reversed?

Prevention is essential, as the damage from diabetes may not be reversed, and complications may be permanent or fatal. However, there is limited research on if the body can heal and reverse the damage.

In 2015, researchers in Japan took a kidney biopsy from a kidney transplant between a patient with diabetes and one without, showing some healing. The result from a 2011 study found that a patient who received a pancreas transplant showed healing in the pancreas, although the healing wasn’t immediate and didn’t take place until 10 years later.

However, cases of reversed diabetic complications, besides in kidney or pancreas transplants, have only been recorded informally. 

A Word From Verywell

Getting diagnosed and treated early for diabetes is the best way to prevent life-threatening complications down the road. Uncontrolled diabetes has the potential to wreak havoc in many of your body’s essential organs and systems, leading to multiple complications.

Learn the signs of untreated diabetes, especially if you have a family history of the condition and other risk factors that may make you more likely to develop type 1 or type 2 diabetes. Even if you weren’t able to catch diabetes early, you can potentially slow down or even reverse the damage by managing it properly.

Frequently Asked Questions

  • How common is untreated diabetes?

    It's hard to say how many people with diabetes are untreated. According to the CDC, more than 100 million Americans have diabetes or prediabetes. It also estimates one in four people who have diabetes are not diagnosed.

  • How is diabetes treated?

    Diabetes is treated with a combination of diet, exercise, and medication. People with type 1 diabetes require insulin to manage their blood sugar. Some people with type 2 diabetes are able to maintain healthy blood sugar levels by limiting carbohydrates and getting enough exercise. Oral and injectable medications are also used to treat type 2 diabetes.

  • How long can you live with untreated diabetes?

    It depends. People with type 1 diabetes require insulin to live. Without insulin, a type 1 diabetic can go into diabetic ketoacidosis, which can be fatal if left untreated. Prior to the introduction of insulin in 1922, people with type 1 diabetes had less than a three-year life expectancy.

    People with type 2 diabetes can remain untreated for much longer. However, high blood sugar will lead to long-term complications over time. This can lead to heart disease, kidney damage, peripheral neuropathy, and vision loss.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. New CDC report: more than 100 million Americans have diabetes or prediabetes.

  2. National Institute of Diabetes and Digestive and Kidney Diseases. What is diabetes?

  3. Cleveland Clinic. Hyperglycemia (high blood sugar).

  4. Centers for Disease Control and Prevention. Diabetes and your heart.

  5. American Diabetes Association. Neuropathy.

  6. Akter K, Lanza EA, Martin SA, Myronyuk N, Rua M, Raffa RB. Diabetes mellitus and Alzheimer's disease: shared pathology and treatment? Br J Clin Pharmacol. 2011 Mar;71(3):365-76. doi: 10.1111/j.1365-2125.2010.03830.x

  7. Harada S, Ushigome H, Nishimura A, Nakao T, Nakamura T, Koshino K, Suzuki T, Itoh T, Nobori S, Yoshimura N. Histological reversibility of diabetic nephropathy after kidney transplantation from diabetic donor to non-diabetic recipient. Nephrology (Carlton). 2015 Jul;20 Suppl 2:40-4. doi:10.1111/nep.12451

  8. Fioretto P, Mauer M. Effects of pancreas transplantation on the prevention and reversal of diabetic nephropathy. Contrib Nephrol. 2011;170:237-246. doi:10.1159/000325747

  9. Distiller LA. Why do some patients with type 1 diabetes live so long? World J Diabetes. 2014;5(3):282–7. doi:10.4239/wjd.v5.i3.282

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