Pre-diabetes or impaired glucose tolerance (IGT) is a condition that puts individuals at higher risk for developing type 2 diabetes. IGT is defined as having a blood glucose level of 140-199 mg percent after consuming 75-100 mg of glucose (or a two-hour oral glucose tolerance test). IGT is also referred to as “borderline or chemical diabetes.”  Pre-diabetes is defined as either a fasting blood glucose level of 100-125 mg percent, or IGT. Type 2 diabetes is defined as having fasting blood glucose over 125 mg percent.

More than 20 million Americans have pre-diabetes, and this number is increasing at epidemic proportions. There are many risk factors that help identify individuals likely to develop pre-diabetes. They are the same risks associated with type 2 diabetes (Figure 1). Most individuals who develop type 2 diabetes, approximately 93 percent of all those with diabetes, are felt to go through a period of years where they have pre-diabetes or IGT before progressing to type 2 diabetes (Figure 2). In the United States, as many as 50 percent of people with pre-diabetes go on to develop type 2 diabetes.

A major medical concern for those with pre-diabetes, besides being at high risk for type 2 diabetes, is the higher risk for vascular disease. Pre-diabetes tends to be associated with other conditions such as:

• Hypertension
• Dyslipidemia (abnormal fat in the blood)
• Abdominal obesity
• Heart disease
• Stroke
• Peripheral vascular disease

Identifying individuals who have pre-diabetes and modifying their risks factors is important in preventing or delaying the onset of type 2 diabetes and vascular diseases.

Recent studies show that lifestyle intervention has a potent effect on pre-diabetes and IGT, delaying the onset of type 2 diabetes, or preventing it all together. Lifestyle intervention consists of:

• Dietary changes
• Modest weight loss
• Exercise, both aerobic and resistance training

In the Diabetes Prevention Program, a study conducted by the National Institutes of Health, the group who participated in the lifestyle intervention had a much better result than those who took medication alone. Lifestyle intervention also helps control blood pressure and blood fats and decreases the risks for vascular diseases.

The most important goal in treating diabetes, pre-diabetes, and IGT is to keep the blood glucose levels as normal as possible (euglycemia). Both lifestyle intervention and medications are used in treatment. Achieving euglycemia has a major impact on preventing complications that occur as a result of chronically high blood glucose (hyperglycemia). These complications include:

• Diseases of the eyes (retinopathy) and blindness
• Diseases of the kidneys (nephropathy) and kidney failure
• Diseases of the nerves (neuropathy)
• Diseases of the blood vessels (heart attacks, strokes, claudication)
• Amputations

Since type 2 diabetes is prevalent (approximately 16 million people in the United States), and associated with complications that seriously affect one’s ability to live a normal lifestyle, it has become a major health-care focus.

Therefore, early recognition of pre-diabetes, beginning lifestyle interventions to prevent diabetes, and treating conditions associated with pre-diabetes such as hypertension and dyslipidemia, give individuals the best opportunity to both prevent or delay the onset of diabetes and have a longer and healthier life.

Risk Factors for Pre-diabetes, IGT, and type 2 diabetes

• Over the age of 45
• Have an immediate family member with diabetes
• Are overweight, especially if they have an increased abdominal girth
• Had gestational diabetes (i.e,. diabetes only when pregnant)
• Have polycystic ovarian syndrome
• Delivered a baby weighing more than nine pounds at birth
• Have high blood sugar levels from steroid therapy
• Are of Native American, Hispanic, African American, Asian American, or Pacific Island descent
• Have hypertension
• Have an abnormal lipid (blood fat) profile
• Have a history of cardiovascular disease