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What Is Prediabetes?


If you receive a prediabetes, it means you have a higher-than-normal blood sugar level that’s not high enough to be diagnostic for diabetes. If you don’t get treatment for it, prediabetes can lead to type 2 diabetes, heart disease, and stroke.

According to the National Institutes of Health (NIH), prediabetes is reversible. Treatment may include lifestyle modifications, such as diet and exercise, and medication. Type 2 diabetes can develop within 10 years if you have prediabetes and don’t make lifestyle changes, says the Mayo Clinic.

The first step for managing prediabetes is understanding what a prediabetes diagnosis means. Read on to learn more about this diagnosis and what you can do.

Other names

Your doctor may refer to prediabetes as the following:

  • impaired glucose tolerance (IGT), which means a higher-than-normal blood sugar after a meal
  • impaired fasting glucose (IFG), which means a higher-than-normal blood sugar in the morning before eating
  • insulin resistance, which means your body can’t use insulin effectively

Insulin resistance leads to a buildup of sugar in the blood.

What are the symptoms of prediabetes?

Prediabetes has no clear symptoms. Some people may experience conditions that are associated with insulin resistance, such as polycystic ovarian syndrome and acanthosis nigricans, which involves the development of dark, thick, and often velvety patches of skin. This discoloration usually occurs around the:

  • elbows
  • knees
  • neck
  • armpits
  • knuckles

If you’ve been diagnosed with prediabetes, it's important to consult your doctor if you experience:

  • increased thirst
  • increased urination, especially at night
  • tiredness
  • blurry vision
  • sores or cuts that won’t heal

These are symptoms typical of type 2 diabetes, and may indicate that your prediabetes has progressed to type 2 diabetes. A doctor can run a series of tests to confirm this.

What are the causes of prediabetes?

The pancreas releases a hormone called insulin when you eat so that the cells of your body can take the sugar from the blood and into the cell for energy. That’s how insulin helps lower your blood sugar level. In the case of prediabetes, the cells don't respond properly to insulin. This is called insulin resistance.

The causes of insulin resistance are unclear. According to the Mayo Clinic, prediabetes is strongly linked to lifestyle factors and genetics.

People who are overweight and sedentary are at an increased risk of prediabetes.

Risk factors for prediabetes

Prediabetes can occur in anyone, but some factors increase your chances. If you’re over 45 years old or you have a body mass index (BMI) higher than 25, your doctor may want to screen you for prediabetes.

Another risk factor is the storage of more fat around the waist than the hips. You can measure this risk factor by checking if your waist is 40 or more inches if you’re male and 35 inches or more if you’re female.

Another risk factor for prediabetes is being sedentary.

How is prediabetes diagnosed?

Your doctor will need to do a blood test for an accurate diagnosis. This means drawing a blood sample to send to a lab.

Results can vary depending on the type of test. You should take the same test twice to confirm the diagnosis, according to the NIH. Devices that measure glucose levels, such as the finger-stick test, aren’t used for diagnosis. Instead, your doctor will use one or two of these tests:

Hemoglobin A1c test

The hemoglobin A1c test, which is also called the A1c test or glycosylated hemoglobin test, measures your average blood sugar level over the last two to three months. This test doesn’t require fasting and can be done anytime.

An A1c value of 5.7-6.4 percent is diagnostic for prediabetes. A second A1c test is recommended to confirm the results. The higher the A1c, the higher the risk that your prediabetes will progress to type 2 diabetes.

Fasting plasma glucose (FPG) test

During an FPG test, your doctor will ask you to fast for eight hours or overnight. Before you eat, a healthcare professional will take a blood sample for testing.

A blood sugar level of 100-125 milligrams per deciliter (mg/dL) indicates prediabetes.

Oral glucose tolerance test (OGTT)

An OGTT also requires fasting. Your doctor will check your blood glucose levels twice, once at the beginning of the appointment and then two hours later after you drink a sugary drink.

If the blood sugar level reads 140-199 mg/dL after two hours, then the test indicates IGT, or prediabetes.

Random plasma glucose (RPG) test

An RPG test can be drawn anytime and doesn’t require fasting. Results with a blood sugar level 140-199 mg/dL indicate prediabetes. Unless you have clear symptoms, you’ll want a second test to confirm a diagnosis.

If testing shows that your blood sugar level is normal, you can repeat screenings in three years. If you're diagnosed with prediabetes, your doctor may recheck your blood glucose level in 12 months or sooner.

How to treat prediabetes

Treating prediabetes can also be thought of as preventing type 2 diabetes. If your doctor diagnoses you with prediabetes, they’ll recommend certain lifestyle changes. A study called the Diabetes Prevention Program showed a reduction of approximately 58 percent in people who kept up with these changes in the long term.

The most common ways to manage prediabetes are:

  • maintaining a diet that’s rich in fiber
  • exercising regularly
  • losing weight
  • taking medication if your doctor prescribed it

Some people with diabetes choose to use complementary and alternative medicine (CAM) treatments to manage their condition. CAM treatments can include taking supplements, meditation, and acupuncture. Always check with your doctor before starting any CAM treatments because they may interact with your medication.

Low-carbohydrate diet

Many studies suggest that a low-carbohydrate diet improves blood glucose control, insulin resistance, and weight. Many people consider a carbohydrate intake of 21-70 grams per day to be low-carbohydrate diet, but no standard definition exists. According to the article, lower levels of carbohydrates may help those with type 2 diabetes, and while it doesn’t address prediabetes specifically, it may be fair to assume the same would be true for those with prediabetes.

Low-carbohydrate diets may not be recommended for people with high cholesterol or heart disease. Talk to your doctor before making major changes to your diet.


If you don’t get treatment for it, prediabetes can become type 2 diabetes and other conditions, such as:

  • heart disease
  • a stroke
  • nerve damage
  • kidney damage
  • eye damage
  • foot damage, in which poor blood flow may lead to amputation
  • skin infections
  • trouble with hearing
  • Alzheimer’s disease

The good news is that prediabetes is reversible with long-term lifestyle changes.

Tips for preventing diabetes

Prediabetes is reversible. You can prevent or slow the development of prediabetes and diabetes through lifestyle changes.

One study showed that a 5 to 7 percent weight loss greatly reduces the risk of diabetes, according to the NIH. Those who participated in the study followed a low-fat, low-calorie diet and exercised for 30 minutes five times per week.

A heart-healthy lifestyle includes the following:

Eating right

Fiber-rich foods, such as fruits, vegetables, and whole grains, will help you reach your health goals. According to the Mayo Clinic, the Mediterranean-style diet follows these principles.

Exercising more

You can reduce your risk of diabetes by being regularly active. Thirty minutes of any activity that raises your heartbeat to your target rate, such as walking, most days of the week, is recommended.

Ways to incorporate physical activity into your daily schedule include:

  • riding a bike to work
  • walking instead of riding the bus or driving
  • going to a gym
  • participating in recreational sports with a team

Thirty minutes of exercise per day and 5-10 percent weight loss reduces your risk of type 2 diabetes progression by over 58 percent, according to the American Diabetes Association.

Content licensed from:

Written by: Brett Huffman and Valencia Higuera
Medically reviewed on: Jul 18, 2016: Peggy Pletcher, MS, RD, LD, CDE

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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