Cocoa Flavanol Supplementation and the Effect on Insulin Resistance in Females Who Are Overweight or Obese: A Randomized, Placebo-Controlled Trial
Elizabeth J. Simpson, Buddhike Mendis, Mandy V. Dunlop, Hagen Schroeter, Catherine Kwik‐Uribe, Ian Macdonald
Abstract
There is interest in the impact that dietary interventions can have on preventing the transition from insulin resistance to type 2 diabetes, including a suggestion that the bioactive components of cocoa may enhance fasting insulin sensitivity. However, a role for cocoa flavanols (CF) in reducing insulin resistance in the insulin-stimulated state, an important risk factor for cardiovascular disease, is unresolved. This study investigated whether CF consumption improved whole-body insulin-mediated glucose uptake (‘M’) in females with overweight/obesity, using a randomized, double-blinded, placebo-controlled, parallel-group design. Thirty-two premenopausal females (19–49 years; 27–35 kg·m−2) with elevated HOMA-IR (HOMA-IR >1.5) supplemented their habitual diet with two servings/day of a high-flavanol cocoa drink (HFC; 609 mg CF/serving; n = 16) or low-flavanol cocoa drink (LFC; 13 mg CF/serving; n = 16) for 4 weeks. Assessment of HOMA-IR and ‘M’ during a 3-h, 60 mIU insulin·m−2·min−1 euglycemic clamp was performed before and after the intervention. Data are the mean (SD). Changes to HOMA-IR (HFC −0.003 (0.57); LFC −0.0402 (0.86)) and ‘M’ (HFC 0.99 (7.62); LFC –1.32 (4.88) µmol·kg−1·min−1) after the intervention were not different between groups. Four weeks’ consumption of ~1.2 g CF/day did not improve indices of fasting insulin sensitivity or insulin-mediated glucose uptake. A recommendation for dietary supplementation with cocoa flavanols to improve glycemic control is therefore not established.