Effect of Intermittent Fasting on Glycaemic Control in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Abstract

Background: Type 2 diabetes mellitus (T2DM) is a severe public health issue notably impacting human life and health expenditure. It has been observed in literature that intermittent fasting (IF) addresses diabetes and its underlying cause, which benefits people with diabetes. Therefore, this study aimed to evaluate the effectiveness of IF treatment on glycaemic control in people with T2DM compared with control group. Methods: Systematic review and meta-analysis of interventional studies among patients with T2DM with glycated haemoglobin (HbA1c) as an outcome was performed. A comprehensive search of electronic databases, including PubMed, Embase and Google Scholar, for articles published before 24 April 2022, was done. Studies reporting 24 hours of complete fasting or intermittent restricted energy intake (feeding permitted for only 4-8 hours daily, with 16-20 hours of fasting) and reporting changes in HbA1c and fasting glucose levels were eligible. Meta-analysis was performed using Cochrane's Q statistic and the I² statistical approach. Results: Eleven studies (13 arms) measuring the effect of IF on patients' HbA1c level were analysed. There was no statistically significant difference between IF and control groups (Standardized mean difference [SMD] -0.08, 95% confidence interval [CI] -0.20 to 0.04;p=0.19, I²=22%). Overall, seven studies on patients' fasting blood glucose were analysed, and the meta-analysis revealed no significant difference between the two groups i.e. IF and control groups (SMD 0.06, 95% CI -0.25 to 0.38;p=0.69, I²=76%). Conclusion: IF and usual diet pattern have no difference in terms of glycaemic control. Although, IF may be used as a preventative diet pattern in the pre-diabetic population, as it works well in the long-term to achieve controlled sugar levels. Study registration: The protocol of this study was registered in The International Prospective Register of Systematic Reviews (PROSPERO) with a registration number CRD42022328528.

Keywords: Diabetes mellitus; diet habits; glycated hemoglobin; glycemic control; intermittent fasting; meta-analysis.

Figure 1.. Study selection, assessment and inclusion

Figure 2.. Risk of bias assessment of the included studies using the Cochrane risk of bias tool for randomized trials on glycaemic control outcomes across seven domains

Figure 3.. Forest plot comparing the effects of intermittent fasting versus control on glycated haemoglobin levels

Figure 4.. Forest plot comparing the effects of intermittent fasting versus control on fasting blood sugar

Figure 5.. Forest plot comparing glycated haemoglobin outcomes based on treatment duration (before and after 12 weeks of treatment) and age (≤60 years and >60 years)

Figure 6.. Forest plot comparing fasting blood glucose outcomes based on treatment duration (≤12 weeks of treatment) and age (≤60 years)

Figure 7.. Funnel plot of glycated haemoglobin level

Figure 8.. Funnel plot of fasting blood sugar level