Administration of resveratrol for 5 wk has no effect on glucagon-like peptide 1 secretion, gastric emptying, or glycemic control in type 2 diabetes: a randomized controlled trial.

Double-blind randomized crossover trial in adults with diet-controlled type 2 diabetes at the Royal Adelaide Hospital in Adelaide, Australia. The active resveratrol arm included 14 participants, with a mean age of 67.5 years, 10 men and 4 women, mean BMI 27.7, and mean baseline HbA1c 6.4%.

Oral resveratrol capsules, 500 mg per dose twice daily, were given for 5 weeks in a double-blind randomized crossover design with a 5-week washout between treatment periods. The intervention was compared with the alternate crossover condition, but the active regimen was resveratrol 500 mg twice daily.

Resveratrol did not improve GLP-1 secretion, gastric emptying, or glycemic control after 5 weeks. In the resveratrol arm, fasting GLP-1 changed from 36.8 to 35.4 pmol/L, peak GLP-1 from 52.7 to 55.1 pmol/L, glucose AUC from 2513 to 2545 mmol/L·min, HbA1c from 6.26% to 6.24%, and gastric half-emptying time from 165 to 163 min. Body weight was unchanged (81.1 to 81.2 kg), and no adverse events were reported. The authors concluded that resveratrol is unlikely to improve glycemic control in this population.

The intervention was short, with only 5-week treatment periods, which limits assessment of longer-term metabolic effects. The study population was small and fairly narrow: elderly adults with diet-controlled type 2 diabetes and no major comorbidities, so generalizability is limited. The crossover design also limits inference to this specific population and timeframe for detecting modest benefits.