Although a majority of Muslim patients with type 2 diabetes fast during the month of Ramadan, there are no accepted guidelines for its management during this period. The few studies on this subject suggest that there are important alterations in energy intake and physical activity, and that most patients change their pattern of drug intake. This is associated with a greater risk of hypoglycaemia and ketoacidosis. The usual pattern of eating during Ramadan, and its influence on the normal diurnal variation of blood sugar with a regular non-fasting diabetic diet, suggests that anti-diabetic agents for use during this period need to be selected according to their pharmacokinetic and tablet formulation characteristics. The sulphonylureas are first line drugs in type 2 diabetes and used by a majority of patients. A comparison of the pharmacokinetics, efficacy, and safety characteristics of these agents suggests that a long-acting once daily formulation of gliclazide such as gliclazide modified release, taken in the evening, may be the sulphonylurea of choice during Ramadan.