Could You Have Prediabetes and Not Know It?

By Athena Philis-Tsimikas, M.D.

Published Nov 12, 2014

With diabetes affecting more than 29 million people in the United States and new cases being diagnosed every day, it may seem surprising to know that diabetes does not develop overnight. Rather, blood glucose levels usually rise over several years due to factors such as poor diet, lack of exercise, obesity, and aging. When blood glucose levels are higher than normal, but not yet high enough for a diabetes diagnosis, you have a condition known as prediabetes — and a significantly increased risk of developing type 2 diabetes within 10 years.
According to the Centers for Disease Control and Prevention, prediabetes affects about 86 million people age 20 and older in the United States. There are usually no symptoms, so most don’t even know they have it unless they have their blood glucose levels tested. Not only is prediabetes likely to lead to full-blown type 2 diabetes, it also can cause serious health problems. Many people with prediabetes will develop conditions often associated with diabetes, such as an increased risk of heart disease, stroke, kidney problems, and other complications. A recent study also found that prediabetes can increase the risk of some types of cancer.

Should You Be Tested?

Since prediabetes generally has no symptoms, the only way to know for sure if you have it is through a blood glucose test. You may be diagnosed with prediabetes if you have impaired glucose tolerance (IGT), impaired fasting glucose (IFG), or a combination of both. IGT means that your blood sugar levels are higher than normal without fasting, while IFG means that your blood glucose levels are higher than normal after you have been fasting.
One of several tests may be used. The fasting plasma glucose test (FPG) measures glucose levels first thing in the morning after you have fasted during the night, since eating or drinking may raise blood glucose. A fasting blood glucose level below 100 milligrams per deciliter (mg/dL) is considered normal; 100 mg/dL to 126 mg/dL is considered “at risk” for diabetes.
The oral glucose tolerance test (OGTT) measures fasting blood glucose levels, and then measures them again after you have consumed a high-glucose beverage. A blood glucose level below 140 mg/dL after the second test is considered normal.
A non-fasting test, HbA1C or the A1C test, measures how well average blood glucose has been controlled over a period of several months. Less than 5.7 percent is considered normal.
In general, you may want to consider testing if you have risk factors for diabetes or prediabetes; for example, if you are overweight, have a family history of diabetes or gestational diabetes, or have high blood pressure or high triglycerides. Ask your physician if you should be tested.

Diabetes Is Not Your Destiny

Having prediabetes does not mean you are destined to develop type 2 diabetes. By taking steps to reduce your risk factors, such as losing excess weight and increasing your exercise, you can lower your risk. In 2001, the Diabetes Prevention Program (DPP), a large prevention study of overweight or obese American adults at high risk of diabetes, found that losing just 5 percent to 7 percent of body weight and increasing exercise helped reduce the risk of developing diabetes by 58 percent. In some cases, participants even saw their blood glucose levels return to normal levels as a result of this treatment. An extension of the DPP study recently reported that, 15 years later, study participants who lost weight and exercised continue to have lower rates of type 2 diabetes than those who did not make lifestyle changes.
If you think you might be at increased risk for diabetes, talk with your doctor about testing and steps you can take to reduce your risk.
Athena Philis-Tsimikas, MD, is an endocrinologist and the corporate vice president for the Scripps Whittier Diabetes Institute at Scripps Health in San Diego.