Gallbladder volume and contractility were measured, by means of real-time ultrasonography, in 48 insulin treated diabetic patients free from autonomic neuropathy, and in 91 healthy control subjects. All controls and diabetic patients were on a isocaloric and balanced diet. Gallbladder measurements were taken after an overnight fast and again 60-75 minutes after each meal. Gallbladder volume was at all times significantly greater in diabetic patients than in controls, while gallbladder contractility was similar. In diabetic patients, but not in controls, gallbladder volume was greater in the elderly than in adults, with no relationship between gallbladder volume and duration of diabetes. It is concluded that enlargement of the gallbladder might be a risk factor for gallstones in diabetic patients.