The effects of resveratrol supplementation on glucose/insulin kinetics and transcription of the AMPK and insulin signaling pathway at rest and following an oral glucose tolerance and graded exercise test in overweight women.

Abstract

The AMPK pathway plays a critical role in glucose metabolism and can potentially improve insulin resistance. Resveratrol is a natural polyphenolic compound that activates this pathway. Therefore, the primary purpose of this study was to determine the effects of daily activation of the AMPK pathway by resveratrol supplementation on glucose/insulin kinetics and transcriptional changes in the AMPK and insulin signaling pathway at rest and following an oral glucose tolerance test (OGTT) and graded exercise test (GXT). Sixteen sedentary, overweight women were recruited for the study. In a randomized and double blind fashion, participants were divided into groups that consumed either 500 mg of resveratrol or a cellulose placebo twice daily for 7 days. On the sixth and seventh day, they returned for an OGTT and a GXT, respectively. Blood and muscle tissue was sampled prior to, and following both the OGTT and GXT. Multivariate analyses revealed no significant changes in resting serum glucose and insulin concentrations (p = 0.255), clinical chemistry safety markers (p = 0.309), or lipid profile panels (p = 0.051) following 7 days of resveratrol supplementation. Following the OGTT, serum glucose concentration was significantly increased 30 min (p < 0.001) and at 1 hr compared to baseline (p = 0.001). However, only a strong trend (p = 0.051) for increased serum insulin concentration was observed following the OGTT. The GXT protocol produced significant changes in serum glucose and insulin concentration. Glucose concentrations were significantly decreased at 1 hr when compared to baseline (p = 0.01) and 30 min (p = 0.032) post-exercise. Insulin concentrations were decreased at 1 hr (p = 0.012) and 2 hrs (p = 0.003) post-exercise. Resveratrol supplementation was unable to enhance such responses. No significant changes were observed with any of the genes analyzed. As a result, it appears that one week of resveratrol supplementation (500 mg/day) is not sufficient to enhance glucose/insulin homeostasis or transcription of metabolically-relevant genes in sedentary, overweight women. Since diabetes is still an increasing global health concern, it is evident that more research is needed to find ways to prevent and/or treat insulin resistance.