Ritual fasting is an essential part of many major faiths. Lent in Christianity, Ramadan in Islam, Yom Kippur in Judaism, or the Navratras in Hinduism – fasts vary in duration and in degree. Some ritual fasts pose challenges to the physical health and fitness of those following the ritual, which are significant in people with diabetes, who have metabolic disorders and use treatments that impair their capacity to fast for long periods of time. With growing numbers of people affected by diabetes worldwide – and as that population grows older, enjoying greater life expectancy with ever-improving diabetes management – the number of people with diabetes wishing to observe religious fasts also looks set to increase. Tint Swe Latt and Sanjay Kalra look at special management issues in the context of Buddhist ritual fasting.