The effect of insulin-induced hypoglycaemia on the gastric emptying rate was studied in eight patients with Type 1 diabetes mellitus of short duration (1-5 years). Gastric emptying was studied using a scintigraphic technique. All patients were studied twice, both during euglycaemia and insulin-induced hypoglycaemia. The blood glucose concentration was adjusted with an insulin-glucose clamp technique. All patients were examined in a standardized way, undergoing the first examination during euglycaemia, with a blood glucose concentration of 4-7 mmol l-1, and the second during hypoglycaemia, with a mean blood glucose concentration of 1.9 +/- 0.3 mmol l-1 at the time of starting the gastric emptying study. During hypoglycaemia both the liquid and the solid gastric emptying rates were significantly increased compared to the rate during euglycaemia. The time to empty 50% of the radioactivity from the stomach for liquid was 48.5 +/- 9.8 min during euglycaemia, compared to 27.6 +/- 20.2 min during hypoglycaemia, p < 0.001. The time to empty 50% of the radioactivity from the stomach for solid food was 48.7 +/- 10.3 min and 23.2 +/- 15.9 min, respectively, p < 0.001. In conclusion, it appears that insulin-induced hypoglycaemia increases the gastric emptying rate in patients with Type 1 diabetes mellitus.