Efficacy of intermittent fasting on blood glucose and weight in type 2 diabetes and prediabetes: A comparison with ad libitum and continuous energy restriction diets.

BACKGROUND AND

OBJECTIVES

This study aimed to evaluate the effects of intermittent fasting (IF) on glycated hemoglobin (HbA1c), fasting blood glucose (FBG), body weight (BW), and body mass index (BMI) in pa-tients with type 2 diabetes mellitus (T2DM) and prediabetes.

METHODS AND STUDY

DESIGN

A systematic search of PubMed, Cochrane Library, Embase, Scopus, and Web of Science was conducted for randomized controlled trials on IF in T2DM and prediabetes published before September 30, 2025. Meta-analysis was performed using RevMan 5.3 and Stata 17.0.

RESULTS

Fourteen studies (sixteen arms), involving 899 patients, were included. Four studies (five arms) compared IF with ad libitum diet (316 patients), and ten studies (eleven arms) compared IF with continuous energy restriction diets (CERD) (583 patients). Meta-analysis showed that IF was more effective than the ad libitum diet in reducing HbA1c, BW, BMI and FBG (Standard-ized Mean Difference (SMD) (Hedges's g) -0.64, 95% Confidence Interval (CI) -1.04, -0.24; p <0.05), (SMD (Hedges's g) -0.30, 95% CI -0.55, -0.05; p <0.05), (SMD (Hedges's g) -0.26, 95% CI -0.51, 0.00; p = 0.05), (SMD (Hedges's g) -0.39, 95% CI -0.64 to -0.15; p <0.05). IF demonstrated effects similar to CERD (p <0.05) in terms of HbA1c, BW, BMI, and FBG. Among 14 studies, dropout rates were 21.5% (IF), 26.2% (CERD), and 15.9% (ad libitum). CERD showed a significantly higher dropout rate than ad libitum, whereas no significant differences were observed between IF and CERD or between IF and ad libitum.

CONCLUSIONS

Intermit-tent fasting is a effective dietary approach for patients with T2DM and prediabetes.