ADA 2010: Promising pilot study of resveratrol

A pilot study of resveratrol in 10 older adults suggests that the compound may be beneficial for patients with impaired glucose tolerance. At doses of 1 to 2 grams daily for 4 weeks, resveratrol significantly increased insulin resistance and lowered postprandial glucose levels.

“The results of this pilot study are preliminary and need to be confirmed in larger numbers of patients,” said lead author Jill Crandall, MD, associate professor of medicine, Albert Einstein College of Medicine, New York, in a prepared statement. “We are encouraged by these findings and plan to conduct additional studies to further explore the potential utility of resveratrol in improving glucose metabolism.”

Resveratrol is found in red grapes, red wine, nuts, berries, and some plants. Preclinical trials have shown that it increases life span in yeast, worms, fruit flies, and rodents, but there is little human data.

The substance is thought to activate sirtuin-1, an NADH-dependent histone deacylase and AMP kinase. It may affect glucose uptake, mitochondrial biogenesis and oxidation, and nitric oxide production.

Researchers gave resveratrol to 10 patients between the ages of 60 and 80 with prediabetes (2-hour fasting glucose 140-199). Outcomes were 3-hour glucose and insulin area under the curve (AUC) following a standard meal, the calculated Matsuda index of insulin sensitivity, and insulin secretion.

The resveratrol dose was given with the meal. Glucose and insulin were measured at 0, 30, 60, 120, and 180 minutes after the meal. Endothelial function was assessed using peripheral arterial tonometry before and 90 minutes after eating. The results did not differ by dose.

Fasting glucose was unchanged after 4 weeks of resveratrol, but postprandial glucose AUC fell from a mean of 469 to 428 (P=.001). The Matsuda index improved from 3.1 to 3.8 (P=.03) and insulin secretion was unchanged, indicating that the major effect was on insulin resistance.

There was a trend to increased postprandial reactive hyperemia index, suggesting improved microvascular endothelial function, but the change was not statistically significant. Weight, blood pressure, and lipids were unchanged, and there were no changes in safety parameters, including chemistries, complete blood count, urinalysis, and electrocardiogram.