Effects of Blood Glucose Concentration on Upper Gastrointestinal Motor and Sensory Function

371 Recent studies have provided important insights into the complex relationships between upper gastrointestinal function and glycemic control in diabetes; it is now recognized that postprandial blood glucose concentrations are both a determinant of, as well as determined by, the delivery of nutrients from the stomach into the small intestine. Furthermore, the prevalence of upper gastrointestinal symptoms, which occur frequently in diabetic patients (1,2), is related to glycemic control (3,4). Disordered gastrointestinal function in diabetes has been attributed to irreversible autonomic neuropathy (5), but it is now clear that acute changes in the blood glucose concentration have a major reversible influence on upper-gut motor and sensory function (6–31). Marked hyperglycemia (blood glucose concentration 15 mmol/l) appears to affect every region of the gastrointestinal tract. Smaller elevations of blood glucose that are within the normal postprandial range (8–10 mmol/l) also influence gut function and may be important in the regulation of gut motility and sensation in healthy individuals. Although it is now accepted that glycemic control, as assessed by HbA1c concentrations, is a major determinant of both the development and progression of diabetic microvascular complications (32,33), the contribution of transient postprandial hyperglycemia has only recently been demonstrated (34). Upper gastrointestinal motor function, particularly the rate of gastric emptying, is a major determinant of postprandial blood glucose concentrations, and there is increasing support for the concept that the modulation of gastric emptying could be used to optimize glycemic control in diabetes (35). The purpose of this review is to summarize current knowledge relating to the effects of the blood glucose concentration on gastrointestinal motor and sensory function and the impact of upper gastrointestinal function on glycemic control.