Prediabetes and Diabetes

According to the National Diabetes Information Clearinghouse, 79 million people in the United States have prediabetes. If you're one of them, you might be wondering why it matters—prediabetes isn't diabetes, is it?

While that is true, many experts consider prediabetes to be the first stage of type 2 diabetes. Studies show that many people with prediabetes go on to develop diabetes within a course of about 10 years. In fact, most people who get type 2 diabetes had prediabetes first. It's also serious in and of itself; those with prediabetes have a greater risk of developing cardiovascular disease than those without it.

So what exactly is prediabetes? It's a condition where your blood glucose levels are above normal, but not high enough for you to be diagnosed with diabetes. There are three tests that doctors do in order to determine whether you have high blood sugar. These are:


This blood test, which is also called HbA1C, hemoglobin A1C or glycosylated hemoglobin, measures the percentage of sugar that is attached to your hemoglobin (a protein in your red blood cells). The higher the A1C, the higher your average blood sugar levels have been running over the past two or three months. A normal A1C is below 5.7 percent. An A1C between 5.7 percent and 6.4 percent suggests prediabetes. you’re an A1C of 6.5 or more is diagnostic for type 2 diabetes. If they diagnosis is questionable, your doctor will retest your A1c on another day to confirm the diagnosis.

Fasting Plasma Glucose

The FPG, or fasting plasma glucose test, is a blood test that is done after you've been fasting overnight. It measures the sugar in your blood. A normal fasting glucose test is lower than 100 mg/dL. A result between 100 and 125 mg/dL is diagnostic for prediabetes. One that is above 126 mg/dL is indicative of diabetes. It is recommended to re-test this another day to confirm the diagnosis.


The oral glucose tolerance test takes a little more time than the other two tests for diabetes. In this test, your blood is taken after an overnight fast and then again two hours after you drink a sugary drink. It's normal for blood sugar to rise after the drink. But normal blood sugar falls to below 140 mg/dL within 2 hours. If it is between 140 and 199 mg/dL, you are diagnosed with prediabetes. Anything 200 mg/dL or above is diagnostic for type 2 diabetes.

Because prediabetes so often leads to diabetes—and because most of the time there are no noticeable symptoms—it's important to have one of these tests, especially if you are overweight or over age 45. For those people who are overweight, testing is recommended if one of these other risk factors is present:

  • physical inactivity
  • an immediate family history of diabetes
  • being of certain ethnicities (African American, Native American, Asian Americans, and Pacific Islanders)
  • women who have had a baby weighing over 9 lbs.
  • blood pressure over 140/90 mmHg
  • good (HDL) cholesterol levels under 35 mg/dL or triglyceride levels over 250 mg/dL
  • an A1c equal to or greater than 5.7% or a high fasting blood sugar (over 100 mg/dL) on a previous test
  • other conditions associated with insulin resistance (polycystic ovarian syndrome, acanthosis nigricans)
  • history of cardiovascular disease

If you do have prediabetes, you can reduce your risk for type 2 diabetes by over 58% by exercising about 30 minutes each day and losing just 5-10% of your body weight. Your doctor may start you on a medication to help control your blood sugar.

Prediabetes does not have to progress to type 2 diabetes. Lifestyle changes can help you get and keep your blood sugar levels within their normal range.