Table 2.

Major risks associated with fasting in patients with diabetes and their potential mechanisms (modified from references 11)*

Hypoglycaemia: Particularly increased in type 1 patients and in insulin-treated type 2 patients. This is due to restricted carbohydrate intake against ongoing action of previously admistered insulin/long acting oral hypoglycaemic agent. Hyperglycaemia: Mainly in the evening time complicating gorging and in day day time complication overzealous reduction of the doses of insulin or oral hypoglycaemic agents. Diabetic ketoacidosis or hyperglycaemic hyperosmolar states: due to absolute or relative insulin deficiency or due to associated intercurrent illness. Dehydration and increased risk of thrombosis: particularly in the poorly controlled or the elderly and in environments of high temperatures particularly when fasting period is long. Risk to the foetus: complicating any of the above.

These form the basis for advice against fasting in different clinical scenarios discussed in Table 3