Type 2 diabetes does not strike without warning. Prediabetes, also known as impaired glucose tolerance (IGT) or impaired fasting glucose (IFG), precedes the condition by months, years, and sometimes even decades. According to the U.S. Department of Health and Human Services, an estimated 57 million Americans have prediabetes — almost as many as are diagnosed with type 2 itself. Many of these people are unaware of their condition.

As the name suggests, prediabetes is defined by blood glucose levels that are higher than normal, but not high enough to indicate diabetes. The actual clinical criterion for a diagnosis of prediabetes is a fasting plasma glucose level of 100 mg/dl (5.6 mmol/l) to 125 mg/dl (6.9 mmol/l) or a two-hour plasma glucose level of 140 mg/dl (7.8 mmol/l) to 199 mg/dl (11.0 mmol/l).

Prediabetes is a signal that without some healthy lifestyle changes, you are most certainly on the path to full-fledged type 2 diabetes. And having prediabetes is a danger in itself. It increases the likelihood of stroke and heart disease by 50 percent.

Am I at Risk?

Known risk factors for both prediabetes and type 2 diabetes include the following:

• Being overweight or obese

• Family history of diabetes

• Low HDL, or “good,” cholesterol (less than 35 mg/dl, or 1.9 mmol/l) and high triglycerides (higher than 250 mg/dl)

• High blood pressure (consistent reading of 140/90 mmHg or higher)

• History of gestational diabetes

• Giving birth to a baby weighing more than 9 pounds

• Belonging to one of the following minority groups: African Americans, Native American Indians, Hispanic Americans/Latinos, and Asian-American/Pacific Islanders