Effect of Time-Restricted Eating on β-Cell Function in Adults With Type 2 Diabetes

Context Time-restricted eating (TRE), which consists of restricting the eating window to typically 4 to 8 hours (while fasting for the remaining hours of the day), has been proposed as a nonpharmacological strategy with cardiometabolic benefits but little is known about its metabolic effect on type 2 diabetes mellitus (T2DM). Objective We evaluated whether TRE can improve pancreatic beta-cell function and metabolic status in overweight individuals with early T2DM. Methods In a randomized, crossover trial, 39 participants (mean 2.9 years of diabetes duration, baseline glycated hemoglobin A1c [HbA1c] 6.6% +/- 0.7% and body mass index [BMI] 32.4 +/- 5.7) were randomly assigned to either an initial intervention consisting of 6 weeks of TRE (20 h-fasting/4 h-eating) or standard lifestyle. The primary outcome of beta-cell function was assessed by the Insulin Secretion-Sensitivity Index-2 (ISSI-2) derived from an oral glucose tolerance test. Results As compared to standard lifestyle, TRE induced a 14% increase in ISSI-2 (+14.0 +/- 39.2%; P = .03) accompanied by a 14% reduction of hepatic insulin resistance as evaluated by HOMA-IR (-11.6% [-49.3 to 21.9]; P = .03). Fasting glucose did not differ between interventions, but TRE yielded a statistically significant reduction in HbA1c (-0.32 +/- 0.48%; P < .001). These metabolic improvements were coupled with a reduction of body weight of 3.86% (-3.86 +/- 3.1%; P < .001) and waist circumference of 3.8 cm (-3.8 +/- 7.5 cm; P = .003). Conclusion TRE improved beta-cell function and insulin resistance in overweight patients with early diabetes, accompanied by beneficial effects on adiposity.