How Untreated Diabetes Affects Your Body

Untreated diabetes is when your high blood sugar level isn’t properly controlled. This is not always a result of someone deciding not to manage their diabetes. It can also happen to those who have diabetes but have not been diagnosed.

Untreated diabetes can potentially cause severe complications that involve almost all parts of your body, including your heart, kidneys, blood vessels, eyes, nerves, gastrointestinal tract, gums, and teeth. In severe cases, it could lead to death.

How Common Is Untreated Diabetes?

According to the Centers for Disease Control and Prevention (CDC), nearly 25% of people with diabetes in the United States were not aware that they had the condition.

Diabetes occurs when your blood sugar, also called blood glucose, is too high (also known as hyperglycemia). Blood glucose is your main source of energy and comes from the food you eat. 

Your body produces a hormone called insulin that helps glucose from food get into your cells to be used for energy. However, sometimes your body doesn’t make enough—or any—insulin or doesn’t use insulin well. As a result, the glucose you consumed stays in your blood and doesn’t reach your cells.

High blood sugar level in the bloodstream can damage various body systems, leading to a wide array of health issues, like heart disease and foot problems. But with the correct treatment and lifestyle changes, many people with diabetes can prevent or delay the onset of these 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 of 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, and it showed some degree of 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.

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8 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.
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  2. National Institute of Diabetes and Digestive and Kidney Diseases. What is diabetes?

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  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

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