Resveratrol supports glucose balance and insulin function, meta-analysis shows
Highlights
- Meta-analysis with 11 randomized, controlled clinical trials
- Median resveratrol supplement intake is 100 mg/day for 12 weeks
- Resveratrol supports glucose balance and insulin function
Summary
This meta-analysis was designed to evaluate the effects of resveratrol on glucose control and insulin sensitivity. Inclusion criteria included randomized, controlled clinical trials published in the peer-reviewed literature (up to March 2014) with estimates of the effects of resveratrol on glucose control and insulin sensitivity.
Eleven studies were included in the meta-analysis for a combined total of 388 subjects who were either healthy (1 study) or had type 2 diabetes (3 trials), cardiovascular disease (3 trials), obesity (3 trials, or metabolic syndrome (1 trial). Resveratrol supplementation ranged from 8 to 1,500 mg/day with a median intake of 100 mg/day. Duration of use varied from 2 weeks to 6 months with a median of 12 weeks.
Results indicate resveratrol had no significant effect in participants without diabetes. However, in participants with diabetes, resveratrol was found to significantly reduce fasting glucose and insulin, glycated hemoglobin, and insulin resistance levels compared to control (see Table). In these studies, the resveratrol dosages were 10 mg/day for 4 weeks, 250 mg/day for 3 months, and 1 g/day for 45 days.
| Parameter | Weighted Mean Difference |
| Fasting Glucose | -35.22 mg/dL (95% CI: -52.13, -18.30 mg/dL; P<.01) |
| Fasting Insulin | -4.55 mIU/mL (95% CI: -6.54, -2.56 mIU/mL; P<.01), |
| HbA1c | -0.79% (95% CI: -1.48, -0.11%; P<.02) |
| HOMA-IR | -2.25 (95% CI: -3.58, -0.93; P<.01) |
| (HbA1c) indicates glycated hemoglobin; HOMA-IR, homeostatic model assessment for insulin resistance. | |
By contrast, no significant effect on glycemic measures was reported for people without diabetes. Subgroup and sensitivity analyses indicated that the pooled effects of resveratrol on fasting glucose and insulin levels in this group were not affected by body mass index (BMI), study design, resveratrol dose, study duration, or study quality (Jadad score).
The researchers suggest three potential mechanisms of action for resveratrol’s effect on glucose control. First, resveratrol can activate the in vivo expression of sirtuin 1, which acts downstream of energy restriction and provides a beneficial effect on glucose control. Second, resveratrol can stimulate glucose uptake by increasing the expression of GLUT4, the insulin-dependent glucose transporter. Third, resveratrol is able to activate glucose uptake in the absence of insulin.
These findings indicate that resveratrol supplementation has clinical value for improving glucose control and insulin sensitivity in people with type 2 diabetes.
