Effects of Ramadan Fasting on Glycaemic Control Among Patients with Type 2 Diabetes: Systematic Review and Meta-analysis of Observational Studies

The prevalence of type 2 diabetes (T2D) is increasing around the world. Although Muslims with a physical illness are exempted from fasting during the month of Ramadan, a great number still choose to fast, often without medical consultations. The aim of this systematic review and meta-analysis was to investigate the impact of observing Ramadan fasting (RF) on glycaemic control in patients with T2D. The Web of Science, Scopus, EBSCOhost, CINAHL, ScienceDirect, Cochrane Library, ProQuest Central and Europe PubMed Central (Medline) databases were searched for relevant studies published between January 2000 and December 2021. Observational studies that examined the changes in body weight (BW) and glucose parameters (glycosylated haemoglobin [HbA1c] and fasting blood glucose [FBG]), before and after RF among different age groups with T2D were included in the systemic review and meta-analysis. Effect sizes for the tested outcomes were calculated as weighted mean difference (WMD), with their confidence intervals (CI). Quality assessment was examined using the National Heart, Lung, and Blood Institute (NHLBI) tool. Of the 1592 identified records, 12 studies conducted in Middle Eastern and Asian countries were eligible and included in the quantitative analyses. The quality of the retrieved studies was evaluated and found to range between fair (83%) and good (17%). These 12 studies included 5554 participants of whom 54% were males and 46% were females. Our pooled analysis demonstrated that HbA1c and FBG levels significantly decreased after RF when compared to the pre-fasting levels (WMD = 0.55 mg/dl, 95% CI 0.33–0.77, P < 0.00001, Ι2 = 93% and WMD = 12.42, CI 6.46–18.38, P < 0.0001, Ι2 = 81%, respectively). However, the difference in BW in fasting patients after RF versus the pre-fasting stage was non-significant. Although, young patients with T2D were enrolled in the 12 selected studies, we did not find any studies that solely focussed on this group. The impact of RF on adult patients with T2D is associated with favorable outcomes. However, future studies should evaluate data from young adults separately. In addition, it is essential to identify the effects of the number of fasting days (level of exposure), diet, level of physical activity and sleeping pattern on optimal glycaemic control. This information could be utilized by medical professionals as a non-pharmacological therapeutic method for management of diabetes in patients who are willing to practice fasting during Ramadan and other months of the year. PROSPERO: CRD42022314752.