About the Study | How Does This Affect You?

Impaired glucose tolerance is a condition in which blood glucose levels are higher than normal but not diabetic. People with impaired glucose tolerance have a high risk of developing type 2 diabetes. Both lifestyle modifications (eg, diet, exercise) and medications have been shown to help prevent or postpone the onset of type 2 diabetes.

A review article published January 19, 2007 by the British Medical Journal examined the results from studies of interventions for the prevention of type 2 diabetes in people with impaired glucose tolerance. The researchers found that medications, lifestyle modifications, and herbal remedies all significantly reduced the risk of progression to type 2 diabetes.

About the Study

For their review, the researchers identified 17 randomized controlled clinical trials that included 8,084 participants with impaired glucose tolerance. All of the studies tested the effects of an intervention to delay or prevent type 2 diabetes. The studies also followed the participants to determine if they developed diabetes. The interventions were either lifestyle (diet and exercise interventions) or pharmacological and herbal (oral diabetes drugs, the anti-obesity drug orlistat, and the Chinese herbal remedy jiangtang bushen).

Using data from the studies' control groups, the researchers calculated that without intervention, about 37% of the participants would develop diabetes over five years. Lifestyle intervention, oral antidiabetes drugs, orlistat, and jiangtang bushen reduced this number by 16, 9, 18, and 23 percentage points, respectively.

These findings are limited because the studies included in the review covered a wide period of time—1979-2006, so the definition of type 2 diabetes and impaired glucose tolerance varied somewhat among the studies.

How Does This Affect You?

According to this study, lifestyle interventions, medications, and herbal remedies are all effective in reducing the risk of type 2 diabetes in people with impaired glucose tolerance. Since it can be assumed that lifestyle modification is associated with fewer risks than medications or herbal remedies, diet and exercise changes should be the treatment of choice for most prediabetic patients.

Another study published in the December 7, 2006 issue of the New England Journal of Medicine compared the effect of three antidiabetes medications--rosiglitazone, metformin, and glyburide--in controlling type 2 diabetes. The researchers concluded that each medication was associated with its own benefits and risks, and that health professionals should weigh the risks, benefits, and costs of each medication before deciding which to use.

Once an antidiabetes medication is chosen, it usually must be increased, changed, or combined with other medications to continue to be effective and/or tolerable. So people with impaired glucose tolerance, which is fundamentally a lifestyle issue, may be able to avoid a lifelong course of medication adjustments and side effects by engaging in a healthy lifestyle, including weight control, a healthful diet, and plenty of exercise.