Ramadan is the fasting month in Islam. Muslims around the world observe Ramadan every year, including people with diabetes. Data on the association of fasting in people with diabetes are sparse. The purpose of this study is to assess the association of fasting on cardiovascular risk factors and events in people with diabetes. A comprehensive search was conducted in the following database: Embase, Medline, Cochrane library and CINAHL. The following key terms were used: Ramadan, Ramazan, Ramadhan, Muslim, Islam and fasting. Studies were eligible if they included people with Type 2 diabetes who fasted during Ramadan and reporting results on cardiovascular risk factors or events. Overall 22 studies met inclusion criteria for the review; five studies reported cardiovascular outcomes and 17 reported changes in risk factors. There is insufficient evidence to link Ramadan fasting with increased or reduced incidence of cardiovascular events in people with diabetes, though there were some indication stroke risk may be increased. Findings were inconsistent in term of risk factors as some favoured Ramadan and others did not.

Introduction

Ramadan occurs in the ninth month of the Islamic calendar. During this month, Muslims around the world abstain from food and drinks, including medications, from sunrise to sunset. Because Ramadan follows the lunar calendar, the length of fasting varies depending on the season [1]. Fasting is obligatory for all adults who are capable, but individuals who may be placed at risk by fasting, such as certain high risk patients with diabetes mellitus, are exempt from fasting [2]. However, as Ramadan fasting is one of the five pillars of Islam, many Muslims insist on fasting in some cases against medical advice [3]. There are about 148 million Muslims globally with diabetes [4]. Most of the available guidelines for people with diabetes planning to fast on Ramadan are based on expert opinions. However, there is a lack of scientific evidence on the safety of fasting in people with diabetes [4,5]. During Ramadan, there is a sudden change in daily routines, including eating and sleeping patterns as well as physical activity levels. Muslims who are fasting consume two meals a day, the first before sunrise (suhur) and the second, which is the main meal, after sunset (iftar). These changes in meal time can be associated with changes in sleeping patterns, such as reduced sleep duration, delayed sleep time and increased sleeping and reduced physical activity levels during the day [6–۸]. Additionally, these changes can result in changes in insulin resistance as well as multiple neurohormonal changes, including the activation of the hypothalamic-pituitary axis and increased catecholamines, which can lead to endothelial dysfunction and increased cardiovascular events [4,9,10]. Furthermore activation of the HPA axis leads to the secretion of cortisol which results in insulin resistance, increased hepatic glucose output and increased gluconeogenesis [11].