Metabolic Impact of Intermittent Fasting in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis of Interventional Studies

CONTEXT: Intermittent fasting (IF) has been proposed as a weight-loss strategy with additional cardiometabolic benefits in individuals with obesity. Despite its growing popularity, the effect of IF in patients with type 2 diabetes (T2DM) remains unclear. OBJECTIVE: We conducted a systematic review and meta-analysis to evaluate the metabolic impact of IF compared to standard diet in patients with T2DM. METHODS: Embase, PubMed, and clinicaltrials.gov between 1950 and August 12, 2020 were searched for randomized, diet-controlled studies evaluating any IF intervention in adults with T2DM. We examined the impact of IF on weight loss and glucose-lowering by calculating pooled estimates of the absolute differences in body weight and glycated hemoglobin A1c (HbA1c) compared to a control group using a random-effects model. RESULTS: Seven studies (n = 338 participants; mean body mass index [BMI] 35.65, mean baseline HbA1c 8.8%) met our inclusion criteria. IF induced a greater decrease in body weight by -1.89 kg (95% CI, -2.91 to -0.86 kg) compared to a regular diet, with no significant between-study heterogeneity (I2 21.0%, P = .28). The additional weight loss induced by IF was greater in studies with a heavier population (BMI > 36) (-3.43 kg [95% CI, -5.72 to -1.15 kg]) and in studies of shorter duration (≤ 4 months) (-3.73 kg [95% CI, -7.11 to -0.36 kg]). IF was not associated with further reduction in HbA1c compared to a standard diet (HbA1c -0.11% [95% CI, -0.38% to 0.17%]). CONCLUSION: Current evidence suggests that IF is associated with greater weight loss in patients with T2DM compared with a standard diet, with a similar impact on glycemic control.