The metabolic effects of intermittent fasting in patients with type 2 diabetes exist in the short term but disappear after its discontinuation: A systematic review and meta-analysis of randomized controlled trials

Abstract

This meta-analysis aimed to determine the short- (< 3 months) and long-term (≥ 3 months) metabolic effects of IF in patients with type 2 diabetes. We hypothesized that IF is non-inferior to other dietary control methods (including continuous energy restriction, standard diet, Mediterranean diet and ad libitum diet) in terms of both short-term and long-term metabolic impacts in patients with type 2 diabetes. We searched for studies in the MEDLINE, EMBASE, and Cochrane Library until August 20, 2023. Studies with non-type 2 diabetes patients, interventions other than IF, no control group, or non-randomized clinical trial designs were excluded. A meta-analysis was then conducted with a random effects model. The Risk of Bias was assessed using the Cochrane risk-of-bias tool (ROB 2). 12 articles with a total of 966 participants were included. IF significantly decreased glycated hemoglobin A1c (HbA1c) (standardized mean difference [SMD]: -0.93; 95% confidence interval [CI]: -1.64, -0.22; P = 0.01), fasting plasma glucose (FPG) (SMD: -0.73; 95% CI: -0.92, -0.54; P < 0.00001) and body weight (SMD: -1.11; 95% CI: -1.92, -0.31; P = 0.007) in the short term compared to control interventions, but showed a similar effect to control interventions in the long term. Substantial heterogeneity existed among our studies. Over the intervention period, long-term IF may safely and feasibly help patients with type 2 diabetes effectively manage blood sugar and reduce body weight, but the metabolic benefits of IF don't endure after its discontinuation. Therefore, continual long-term IF may provide more lasting metabolic benefits.

Keywords: Intermittent fasting; Long-term metabolic effects; Short-term metabolic effects; Time-restricted eating; Type 2 diabetes.