Gastric emptying is delayed in 30%-50% of patients with longstanding diabetes mellitus. The prevalence of disordered gastric emptying in patients with "early" Type 2 diabetes is controversial, but it has been suggested that gastric emptying is often accelerated. The pathogenesis of delayed gastric emptying in diabetes is poorly understood. It is, however, clear that acute changes in the blood glucose concentration have a major effect on gastric motor function and gastric emptying. There is an inverse relationship between the rate of gastric emptying and the blood glucose concentration, so that emptying is slower during hyperglycaemia and faster during hypoglycaemia. The motor dysfunctions responsible for delayed gastric emptying in patients with diabetes are heterogeneous. There is a high prevalence of upper gastrointestinal symptoms in diabetes. However, the correlation between symptoms and delay in gastric emptying is poor. Recent studies indicate that the blood glucose concentration modulates the perception of some sensations arising from the gastrointestinal tract. In both normal subjects and patients with diabetes the blood glucose response to oral carbohydrate and gastric emptying are related and there is evidence that modulation of the rate of gastric emptying, by dietary or pharmacological means, could be used to optimise glycaemic control. The use of prokinetic drugs, particularly cisapride, is currently the most effective approach to the treatment of symptomatic patients with gastroparesis. An improved understanding of the pathophysiology of both symptoms and delayed gastric emptying is fundamental to the development of more effective treatments.