A review of Ramadan fasting and diabetes mellitus: Controversies regarding the effects of Ramadan fasting on diabetic patients

Although several studies have investigated the effects of Ramadan fasting on diabetic patients, the exact impacts on diabetes control have not been well elucidated yet. There are neither precise quantitative criteria nor clear guidelines regarding Ramadan fasting for diabetic patients. This review aimed to discuss the results of previous studies. The neglected points in performed studies should be considered in the design and interpretation of future research related to Ramadan fasting in diabetic patients. A thorough research was carried out on the internet, using the following keywords: “Ramadan”, “Ramadan fasting”, “Islamic fasting”, “fasting in Ramadan”, and “fasting”, in combination with words such as “diabetes mellitus”, “hyperglycemia”, “hypoglycemia”, and “diabetic ketoacidosis”. Databases including PubMed, Google Scholar, and some regional databases were searched in order to find related articles (cross-sectional, descriptive-analytical, cohort, clinical trial, and review studies), published during 1957-2013. The obtained data showed that Ramadan fasting could be non-risky for partially controlled diabetic patients. However, the safety of Ramadan fasting for diabetic patients with different blood glucose levels and complications is not yet determined. Many deficiencies and limitations are observed in the related studies such as the heterogeneity of participants including differences in lifestyle and circadian rhythm changes. Therefore, well controlled studies need to be performed to evaluate factors affecting blood glucose level during Ramadan fasting.