Effects of Ramadan fasting on glycemic control and lipid profile in type 2 diabetes mellitus: a systematic review and meta-analysis of clinical studies

BACKGROUND: Fasting is believed to confer metabolic health benefits; however, evidence regarding its effectiveness in patients with type 2 diabetes mellitus (T2DM) remains inconsistent. This study aimed to evaluate the effects of Ramadan fasting (RF) on the glycemic control, lipid profiles, and safety of patients with T2DM. METHODS: PubMed/MEDLINE, Web of Science, Scopus, ScienceDirect, and the Cochrane Library were searched for clinical studies published until March 2026. Glycemic and lipid outcomes were pooled using a random-effects model and reported as mean differences (MDs) with 95% confidence intervals (CIs). The proportions of hypoglycemia and hyperglycemia were pooled using random-effects meta-analysis. RESULTS: Thirty-four clinical studies involving 11,925 adults with T2DM were included. RF significantly improved fasting blood glucose (MD, -11.45; 95% CI, -17.48 to -5.42; p<0.01), glycated hemoglobin (MD, -0.46; 95% CI, -0.65 to -0.27; p<0.01), low-density lipoprotein (MD, -6.31; 95% CI, -11.81 to -0.81; p=0.02), and triglycerides (MD, -15.16; 95% CI, -25.97 to -4.34; p=0.01). No noteworthy improvements were observed in total cholesterol (MD, -9.38; 95% CI, -19.97 to 1.20; p=0.08) and high-density lipoprotein (MD, 0.81; 95% CI, -1.45 to 3.08; p=0.48). Substantial heterogeneity (I2=91%-97%) was observed across all outcomes. The pooled proportions of hypoglycemia and hyperglycemia were 6% (95% CI, 3%-10%) and 7% (95% CI, 0%-21%), respectively, with substantial heterogeneity (I2>96%). CONCLUSION: RF was associated with an average reduction in glycemic and certain lipid parameters, but hypoglycemia and hyperglycemia remained non-negligible risk factors. These findings should be interpreted as context-dependent associations across heterogeneous populations, rather than as a uniform effect of RF. Individualized monitoring and appropriate therapeutic adjustments are essential during RF.