Metformin may delay diabetes onset in those at risk

NEW YORK (Reuters Health) - In people who are at risk of developing diabetes, treatment with metformin leads to modest improvements in weight, lipid (fat) profiles and fasting blood sugar. In addition, substantial reductions in insulin resistance, a condition that usually precedes diabetes, are seen, as well as the actual development of diabetes, according to a large review of published studies on this topic.

Dr. Shelley R. Salpeter from Stanford University School of Medicine, California and colleagues combined data from 31 trials that compared metformin with placebo or no treatment in a total of 4570 adults at risk for diabetes. Metformin comes in a long-acting tablet form and is sold under several trade names, such as Glucophage and Fortamet.

Metformin, compared with the other two groups, reduced body mass index by 5.3 percent, fasting blood sugar by 4.5 percent, fasting insulin by 14.4 percent, and calculated insulin resistance by 22.6 percent, according to the report in the American Journal of Medicine.

Metformin treatment also reduced levels of lipids circulating in the blood, including triglycerides and LDL cholesterol by 5.3 percent and 5.6 percent, respectively. These factors are all considered to increase the risk of diabetes and cardiovascular disease.

Conversely, HDL cholesterol levels, the "good cholesterol," increased by 5.0 percent compared with placebo or no treatment.

After an average of nearly two years, the rate of new cases of diabetes was reduced by 40 percent, the investigators found.

Salpeter and colleagues think metformin could be added to diet and exercise if lifestyle modifications, such as dieting and exercise, alone are not sufficient to reduce the risk of diabetes in high-risk individuals.

Additional long-term clinical trials will be needed to clearly show that the benefits of metformin treatment result in a reduction in cardiovascular disease and death, they conclude.

SOURCE: American Journal of Medicine, February 2008.