Disordered gastric emptying occurs in 30-50% ofpatients with diabetes mellitus. Although the rate ofgastric emptying is dependent on the integration ofmotor activity in different regions of the stomach, there is limited information about the functionof the proximal stomach in diabetes mellitus. In thepresent study the response of the proximal stomach to aliquid meal was examined in eight diabetic patients with autonomic neuropathy and gastrointestinalsymptoms and in 10 healthy volunteers, using anintragastric bag connected to an electronic barostat.Postprandial relaxation of the proximal stomach wasmeasured as an increase of intragastric bag volume at aconstant pressure level of 1 mm Hg above theintraabdominal pressure. During the experiment the bloodglucose levels were maintained within the euglycemic range. Before ingestion of the meal theintragastric bag volume was larger in the diabeticpatients than in the healthy volunteers, 234.4 ±29.1 ml vs 155.3 ± 15.3 ml (P = 0.06). Themaximum volume was not different in diabetics compared to the healthy controls(386.3 ± 45.2 ml versus 399.0 ± 35.2 ml).However, the maximum volume increase was significantlyless in diabetics (143.7 ± 38.6 ml) compared tothe controls (231.4 ± 30.5 ml, P < 0.04). Bloatingwas inversely correlated with the volume changes, whichsuggests that impaired relaxation of the proximalstomach may play a role in the genesis of thissensation. In conclusion, this study shows a lower fastingfundal tone and a decrease in volume change of thegastric fundus after a nutrient drink in patients withautonomic neuropathy due to type I diabetes mellitus. These abnormalities may play a role in theabnormal distribution of food, disordered liquid gastricemptying, and in the genesis of the sensation ofbloating observed in these patients.