Prediabetes (Borderline Diabetes)

What Is Prediabetes?

Prediabetes is a health condition that means your blood sugar level is higher than normal, but not yet high enough for you to be diagnosed with diabetes.

The blood sugar range for prediabetes is 100-125 milligrams per deciliter (mg/dL), and the A1c range is 5.7% to 6.4%. The A1c averages your blood sugar over 2 to 3 months.

Prediabetes usually has no symptoms, but it almost always shows up before you get diagnosed with diabetes.

About 86 million people in the U.S. over age 20 have prediabetes. And doctors see the need to diagnose it more often. Treating it can prevent more serious health problems later on. These range from type 2 diabetes to problems with your heart, blood vessels, eyes, and kidneys.

By the time you’re diagnosed with diabetes, many of these problems have already taken hold.

Signs and Symptoms of Prediabetes

Although most people with prediabetes have no symptoms, you might notice:

  • You're extra thirsty.
  • You pee a lot.
  • Your vision is blurry.
  • You’re extremely tired.

Risk Factors and Causes of Prediabetes

You’re most likely to get this disease if you:

Get tested for prediabetes if you meet the criteria above and you:

  • Had an abnormal blood sugar reading in the past
  • Have heart disease
  • Show signs of insulin resistance, which means your body produces insulin but doesn't respond to it the way it should


Tests and Diagnosis for Prediabetes

Your doctor can do one of three different blood tests -- the fasting plasma glucose test, the oral glucose tolerance test, or the hemoglobin A1c test.

Fasting plasma glucose test: You won’t eat for 8 hours before thig blood test. The results are:

  • Normal if your blood sugar is less than 100 mg/dL
  • Prediabetes if your blood sugar is 100-125 mg/dL
  • Diabetes if your blood sugar is 126 or higher mg/dL

Oral glucose tolerance test: First, you'll take the fasting glucose test. Then you'll drink a sugary solution. Two hours after that, you'll take another blood test. The results are:

  • Normal if your blood sugar is less than 140 mg/dL after the second test
  • Prediabetes if your blood sugar is 140-199 mg/dL after the second test
  • Diabetes if your blood sugar is 200 mg/dL or higher after the second test

Hemoglobin A1c test: This blood test shows your average blood sugar level for the past 2 to 3 months. Doctors can use it to diagnose prediabetes or diabetes. Or if you already know you have diabetes, it helps show whether it's under control. The results are:

  • Normal: 5.6% or less
  • Prediabetes: 5.7 to 6.4%
  • Diabetes: 6.5% or above

You may need to take the test again to confirm the results.

Treatment to Reverse Prediabetes

Treatment for prediabetes is simple:

  • Eat a healthy diet and lose weight. Losing 5% to 10% of your weight can make a huge difference.
  • Exercise. Choose something that you enjoy, like walking. Try to get at least 30 minutes a day, 5 days a week. You can start with less time and work your way up to a half-hour if you need to. Check with your doctor before you do more than that.
  • Stop smoking.
  • Treat high blood pressure and high cholesterol.
  • Take medication like metformin (Glucophage) to lower blood sugar if you’re at high risk of diabetes.


Is There a Prediabetes Diet?

There’s no official diet, but four simple changes can reverse prediabetes and lower your risk of type 2 diabetes:

  • Choose whole grains and whole-grain products over processed carbs like white bread, potatoes, and breakfast cereals.
  • Drink coffee, water, and tea instead of sugary drinks.
  • Opt for good fats like those in vegetable oil, nuts, and seeds over those in margarine, baked goods, and fried foods.
  • Trade red meat and processed meats for nuts, whole grains, poultry, and fish.

WebMD Medical Reference Reviewed by Michael Dansinger, MD on June 12, 2019



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National Diabetes Clearinghouse: “Insulin Resistance and Pre-Diabetes.”

Shoelson, S. Journal of Clinical Investigation, 2006.

Phillips, L. Diabetes Care, 2006.

Kim, S. Journal of the American College of Cardiology, 2006.

Mayo Clinic: “Prediabetes.”

Harvard School of Public Health: “Simple Steps to Preventing Diabetes.”

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