Most Muslims with diabetes will take part in Ramadan even though they may be exempt from doing so. In some countries a religious fast can last between 10 and 21 hours. The main risk of fasting to people with diabetes is hypoglycemia. People with diabetes who fast may have to alter the dose of their medications or modify their therapeutic regimen to avoid hypoglycemia, which can have adverse effects on glycemic control. Therapies which pose a high risk of hypoglycemia when used during fasting are sulfonylureas and insulin therapy. Metformin, incretin therapies and the newer sodium glucose co-transporter 2 inhibitor class have a low risk of hypoglycemia. The practice of fasting during Ramadan is advocated for all healthy individuals. If deemed detrimental to health then a person can be considered exempt from fasting; this includes frail and elderly people, pregnant and breast feeding women, children and people with multi-morbidities.