Symptoms of Prediabetes

Approximately 38% of adults and 28% of children in the United States have prediabetes, a health condition associated with abnormally high blood sugar levels. While blood sugar (glucose) levels are elevated in prediabetes, they are not high enough to be diagnosed as type 2 diabetes.

This article highlights the possible symptoms of prediabetes, including extreme thirst, frequent urination, and blurry vision. It also reviews the complications that may arise if the condition is not managed.

Thirsty woman drinking water in kitchen

Jessica Peterson / Getty Images

Possible Symptoms

Prediabetes is not a harmless condition since it predates the onset of type 2 diabetes, a chronic disease that could result in disorders of the circulatory system, the nervous system, and the immune system.

Most children and adults with prediabetes do not have symptoms, especially early on in the disease.

If prediabetic symptoms do exist, they most commonly include one or more of the following:

Excessive Thirst

Excessive thirst, also called polydipsia, results from high blood sugar (glucose) levels in the body.

Usually, glucose in your bloodstream is filtered and reabsorbed in your kidneys. With high glucose levels, however, the proteins that typically bind to and reabsorb glucose within your kidneys become saturated.

As a result, glucose is not reabsorbed but released into the urine, where it naturally draws water in. When glucose leaves your body through the urine taking water with it, your brain's thirst response is triggered to replete the lost water volume.

Ensure Adequate Hydration

If you have prediabetes and are feeling thirsty, it's essential to stick to water or caffeine-free drinks like seltzer water, herbal tea, or sugar-free lemonade. Remember also to limit your alcohol intake since alcohol contains sugar and can dehydrate you.

Frequent Urination

Frequent urination, also called polyuria, typically goes hand in hand with excessive thirst.

Large amounts of water are released through the urine when your blood sugar levels are elevated. This water loss in your urine can lead to tissue dehydration and symptoms like nausea, dizziness, headaches, constipation, and fainting.

If you feel the urge to urinate frequently, with no other apparent cause (such as from having consumed excessive caffeinated drinks), reach out to your healthcare provider. This could be a sign of prediabetes.

Blurry Vision

Most studies report that 5% or more of people with prediabetes have diabetic retinopathy, a complication of elevated blood sugar levels caused by damage to the blood vessels in the retina (tissue at the back of the eye).

Blurry vision is a prominent, early symptom of diabetic retinopathy.

Additional symptoms may include:

  • Seeing dark or floating spots
  • Trouble reading or driving
  • Impaired color vision

If you are experiencing blurry vision, it's important to see your healthcare provider and have your blood sugar levels checked. 

Undergo Screening Eye Exams

If you have already been diagnosed with prediabetes, be sure to see an eye care professional, such as an ophthalmologist (a doctor specializing in eye diseases), for periodic screening eye exams. This remains true even if you are not experiencing any vision changes.

Other Prediabetic Symptoms

Other possible symptoms of prediabetes to watch out for include:

  • Unusual tiredness
  • Sores or cuts that won't heal
  • Numbness and tingling of the feet, toes, hands, and fingers
  • Increased hunger
  • Dark patches of velvety skin on the back of your neck, armpit, or groin—what's known as acanthosis nigricans
  • Unintended weight loss
  • Frequent skin infections (e.g., yeast infections)

Rare Symptoms

Two rare but potentially life-threatening conditions that may develop in people whose prediabetes has progressed to type 2 diabetes (perhaps without their knowing it) are:

Diabetic Ketoacidosis (DKA)

Diabetic ketoacidosis occurs when the body breaks down fat, producing toxic acids called ketones. The body does this in response to insufficient insulin levels. Insulin is a hormone that helps move blood sugar into cells, which can be used for energy.

Symptoms of DKA may include:

  • Frequent urination
  • Extreme thirst
  • Dry mouth
  • Headaches
  • Nausea or vomiting
  • Stomach pain
  • Fruity-smelling breath

Hyperglycemic hyperosmolar nonketotic syndrome (HHNS)

HHNS involves extremely high blood sugar levels leading to severe dehydration. It's most common in older adults but can occur in children and adolescents.

Symptoms of HHNS may include:

  • Frequent urination
  • Extreme thirst
  • Dry mouth
  • Drowsiness
  • Weakness
  • Confusion
  • Passing out

Complications of Prediabetes

Most complications of prediabetes manifest as a result of long-standing and untreated high blood sugar levels.

If not treated, prediabetes can progress to type 2 diabetes and cause these complications:

  • Diabetic nephropathy: Kidney damage from high blood sugar levels may lead to kidney failure.
  • Diabetic neuropathy: Nerve damage (neuropathy) may cause pain (tingling, burning, sharp, or shooting sensations), walking difficulties, and fall-related injuries.
  • Diabetic eye disease: This includes diabetic retinopathy, macular edema (swelling of the retina), cataracts (clouding of the lens), and glaucoma (buildup of pressure within the eye).
  • Heart attack: You may lose blood to part of your heart muscle, resulting in a myocardial infarction (heart attack).
  • Stroke: Blood supply to your brain may be blocked or interrupted or a blood vessel in the brain may burst.
  • Peripheral artery disease: Blockage of the arteries supplying blood to your limbs, head, or abdomen can cause foot sores and ulcers and loss of a limb (amputation).

When to See a Healthcare Provider

See your healthcare provider if you notice any symptoms or signs of prediabetes, such as feeling thirsty, hungry, or tired more than usual, urinating more frequently, or experiencing blurry vision.

If left undiagnosed, prediabetes can develop into type 2 diabetes and cause serious damage to vital organs, including the kidneys, eyes, nerves, heart, and blood vessels. 

The good news is that lifestyle changes, such as eating nutritiously, losing weight if overweight or obese, staying physically active, and quitting smoking, can delay, if not prevent, the onset of type 2 diabetes.

Summary

Prediabetes is a health condition in which a person’s blood glucose levels are higher than usual but below the threshold for a diagnosis of diabetes. Most people with prediabetes have no symptoms; if they do, symptoms are often subtle. They may include excessive thirst, a frequent urge to urinate, or blurry vision, among others.

If prediabetes is not managed, it can develop into type 2 diabetes, and complications involving the eyes, nerves, blood vessels, and kidneys may occur.

A Word From Verywell

Even if you are not experiencing any prediabetic symptoms (or they are subtle), do not hesitate to get your blood sugar levels checked. Earlier detection means more time to take control of your health and prevent type 2 diabetes.

The American Diabetes Association recommends that all adults begin screening for prediabetes or diabetes at the age of 35.  Screening is also recommended for children who have entered puberty or are at least 10 years old, are overweight or obese, and have at least one other risk factor for type 2 diabetes.

Frequently Asked Questions

  • What are the early warning signs of prediabetes?

    Even though most people with prediabetes have no symptoms, early ones may include excessive thirst, frequent urge to urinate, blurry vision, and extreme tiredness.

  • How can you prevent prediabetes from developing into diabetes?

    Certain lifestyle behaviors, including eating nutritiously, maintaining a healthy weight, and staying physically active can delay, if not prevent, prediabetes from developing into diabetes.

  • Are skin tags a sign of prediabetes?

    Skin tags are benign (harmless) outgrowths of normal skin that are common in adults and increase with age. Research suggests they may be a sign of prediabetes and other conditions, including high blood pressure and high cholesterol.

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.
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By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.