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The Dangers of Prediabetes

What you need to know if your blood sugar level is in the prediabetes range.
By Winnie Yu
WebMD Feature
Reviewed by Laura J. Martin, MD

Colleen Schultz was stunned to learn that her blood sugar level was high during a routine doctor visit in the fall of 2010. Though she did not have diabetes, her results were in the prediabetes range. "I was very upset," says Schultz, a drapery fabricator in Voorheesville, N.Y. "It was depressing thinking I was falling apart. I didn't want to take medications for the rest of my life."

Her doctor gave her a prescription, which Schultz tried and then decided she'd rather focus on her doctor's other advice: Eat better and get more exercise. With her doctor's approval, she did just that. Schultz gave up alcohol and fried foods and took up walking, yoga, and Zumba. In three months, Schultz lost 11 pounds, and her blood sugar level dropped, though she still had prediabetes.

Schultz is one of the estimated 79 million people in the U.S. who have prediabetes, a condition in which blood sugar levels are slightly elevated, but not high enough to qualify for diabetes. Having prediabetes increases a person's risk of developing type 2 diabetes within the next 10 years.

"Whether prediabetes is a disease or not is a matter of opinion (among doctors and health care companies) but it's clearly a wake-up call, and people who have it have to do something about it," says Edward Horton, MD, a professor of medicine at Harvard Medical School and a senior investigator at the Joslin Diabetes Center in Boston. "As a society, we have to take it seriously."

Making the Diagnosis

Determining whether you have prediabetes typically involves undergoing a fasting plasma glucose test (FPG) or an oral glucose tolerance test (OGTT). Both are blood tests that require an overnight fast.

Normal fasting blood glucose is below 100 mg/dl. Prediabetes is defined as a fasting blood glucose level between 100 and 125 mg/dl. If a person has at least two fasting blood glucose levels at 126 mg/dl or above, they have diabetes.     

For the OGTT, a person's blood glucose is measured after a fast and two hours after drinking a glucose-rich beverage. Normal blood glucose drops below 140 mg/dl two hours after the drink. But if you have prediabetes, your two-hour blood glucose is between 140 and 199 mg/dl. If your two-hour blood glucose is 200 mg/dl or above, you have diabetes.

Some doctors may also use the A1C test, or glycated hemoglobin test. This test measures your average blood sugar level for the past two-to-three months. A level between 5.7 and 6.4 is prediabetes.

Knowledge Is Power

Unlike Schultz, few people with prediabetes know they have it. "Most people are not diagnosed with prediabetes because many doctors may never have that conversation with their patients," says Ann Albright, PhD, RD, director of the CDC's division of diabetes translation. She says that in a CDC study, only 7% of patients said they have ever been told that they have prediabetes.

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If the level is below 70 or you are experiencing symptoms such as shaking, sweating or difficulty thinking, you will need to raise the number immediately. A quick solution is to eat a few pieces of hard candy or 1 tablespoon of sugar or honey. Recheck your numbers again in 15 minutes to see if the number has gone up. If not, repeat the steps above or call your doctor.

People who experience hypoglycemia several times in a week should call their health care provider. It's important to monitor your levels each day so you can make sure your numbers are within the range. If you are pregnant always consult with your health care provider.

Congratulations on taking steps to manage your health.

However, it's important to continue to track your numbers so that you can make lifestyle changes if needed. If you are pregnant always consult with your physician.

Your level is high if this reading was taken before eating. Aim for 70-130 before meals and less than 180 two hours after meals.

Even if your number is high, it's not too late for you to take control of your health and lower your blood sugar.

One of the first steps is to monitor your levels each day. If you are pregnant always consult with your physician.

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