Ramadan, one of the five pillars of Islam, is a holy month for Muslims. During this month, they have a duty to fast every day from sunrise to sunset. This religion spares diabetics and persons with chronic illnesses from this duty, because lack of eating and drinking all the day has many bad consequences on their health. But, because of a very strong habit, by solidarity with the family, or by fear of exclusion from the society, many diabetics insist on fasting as demonstrated by numerous studies. The problem is, when they fast, diabetics are at risk from complications such as severe hypoglycemia, hyperglycemia, ketoacidosis, dehydration and thrombosis. To avoid this, consensus and recommendations have emerged in order to develop new approaches that would minimize the various complications. It appears from different recommendations that only diabetics whose equilibrium is stable, free of degenerative complications, and able to manage properly their diseases will be allowed to fast. The physician's role is to assist the faithful person to Ramadan by raising awareness of lifestyle and dietary rules, daily self-monitoring, and a new adjustment of treatment.