A systematic review, meta-analysis, and meta-regression of the impact of diurnal intermittent fasting during Ramadan on glucometabolic markers in healthy subjects

Abstract Aim Studies on the effect of Ramadan diurnal intermittent fasting (RDIF) on glucometabolic markers have yielded conflicting results. We conducted a meta-analysis to estimate the effect size for changes in glucometabolic markers in healthy, non-athletic Muslims during Ramadan, and to assess the effect of variable covariates using meta-regression. Methods CINAHL, Cochrane, EBSCOhost, EMBASE, Google Scholar, ProQuest Medical, PubMed/MEDLINE, ScienceDirect, Scopus, and Web of Science databases were searched from date of inception to January 2020. The glucometabolic markers analyzed were: fasting glucose (FG), insulin, insulin resistance (HOMA-IR), leptin, and adiponectin. Results We identified seventy-two studies (3134 participants in total) that were conducted in 22 countries between 1982 to 2020. RDIF-induced effect sizes for the glucometabolic markers were: FG (no. of studies K=61, number of subjects N=2743, Hedges' g = -0.102, 95% CI: -0.194, -0.01); serum insulin (K=16, N= 648, Hedges' g =0.030 95% CI: -0.165, 0.226); HOMA-IR (K=10, N=349, Hedges' g = -0.012, 95% CI: -0.274, 0.250); leptin (K=13, N=442, Hedges' g = -0.010, 95% CI: -0.243, 0.223); and adiponectin (K=11, N=511, Hedges' g =0.034, 95% CI: -0.227, 0.296). Conclusion RDIF imposes no adverse metabolic impacts, and might help in improving some glucometabolic markers in healthy subjects.