Polyphenols from berries are associated with many beneficial effects on health, but their impact on insulin sensitivity in humans is unknown. The six-week study was parallel, randomized, double blind, placebo controlled and studied 41 insulin-resistant subjects who were overweight or obese. Participants were between the ages of 40 and 65.
Participants in the experimental group consumed the polyphenol liquid supplement (333 mg of polyphenols) daily, while the control group consumed a placebo. A hyperinsulinemic-euglycemic clamp, for assessing insulin sensitivity, and a two-hour oral glucose tolerance test were performed before and after the experimental period.
The polyphenols from the berries improved insulin sensitivity by 31 percent, and prevented an increase in insulin secretion, which could lead to an alternative approach to Type 2 diabetes.