Gastric emptying following the ingestion of 200 ml orange juice was investigated sonographically in 24 insulin-dependent diabetics with and without autonomic neuropathy and in 11 control subjects. Furthermore, the relationship between emptying and blood glucose was determined. The duration of gastric emptying in all patients was negatively correlated with the heart rate variation (P less than 0.01) and was longer in patients with autonomic neuropathy than in control subjects or patients without autonomic neuropathy (t1/2 48 +/- 12 min vs. 20 +/- 9 min and 24 +/- 5 min, respectively, P less than 0.0005). The rise in blood glucose was positively correlated with the heart rate variation in all patients (P less than 0.01) and was slower in autonomic neuropathy (1.2 vs. 2.9 mg/dl X min, P less than 0.0005). The delayed carbohydrate absorption in autonomic neuropathy with slower gastric emptying could be important in the management of diabetic patients in whom metabolic control is difficult.