Being Diagnosed

How is diabetes diagnosed?

There are several ways to diagnose diabetes. Testing should always be done by healthcare professionals (a doctor’s office or a lab).

A1C Test

The A1C test measures your average blood glucose (sugar) for the past two to three months. The advantages of being tested this way are that you don’t have to fast (not eat). Diabetes is diagnosed at an A1C of more than or equal to 6.5%.


Fasting Plasma Glucose (FPG) Test

This test checks your fasting blood glucose levels. Fasting means not having anything to eat or drink (except water) for at least eight hours before the test. This test is usually done first thing in the morning, before breakfast. You’ll be diagnosed with diabetes if your fasting blood glucose is more than or equal to 126 mg/dl.

Oral Glucose Tolerance (OGTT) Test

The OGTT is a two-hour test that checks your blood glucose levels before and two hours after you drink a special sweet drink. It tells the doctor how your body uses glucose. Diabetes is diagnosed at two hour blood glucose of more than or equal to 200 mg/dl.

What is prediabetes?

Before people develop type 2 diabetes, they almost always have “prediabetes”—blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes.

Doctors sometimes refer to prediabetes as impaired glucose tolerance (IGT) or impaired fasting glucose (IFG), depending on what test was used when it was detected. This condition puts you at a higher risk for developing type 2 diabetes and cardiovascular disease.

There are no clear symptoms of prediabetes, so you may have it and not know it. Some people with prediabetes may have some of the symptoms of diabetes or even problems from diabetes already. You usually find out that you have prediabetes when being tested for diabetes.

If you have prediabetes, you should be checked for type 2 diabetes every one to two years.

What to do once you’ve been diagnosed with diabetes

It’s not easy to hear you have diabetes. But for millions of Americans, learning about their diabetes is the first step toward feeling better and living a longer, healthier life. Download the diabetes book as a first step to learning about your diagnosis.