Fasting is obligatory for all Muslim men and boys over the age of 12 and for Muslim women and girls who have passed puberty. It requires that no food or drink pass the lips during the hours of daylight, including medication – oral or inhaled. Not eating or being unable to take medication during the daytime obviously has major implications for people with diabetes. In this article we review how we should advise our patients – how can they maintain control of their diabetes at the same time as honouring their religious obligations?