Context: The rate of gastric emptying of carbohydrate is a major determinant of postprandial glycemia. In healthy subjects and patients with uncomplicated type 1 diabetes, there is evidence that gastric emptying may be accelerated by insulin-induced hypoglycemia.
Objective: The objective was to determine the effects of acute hypoglycemia on gastric emptying in long-standing type 1 diabetes and evaluate whether the response to hypoglycemia is influenced by the rate of gastric emptying during euglycemia and/or autonomic dysfunction.
Design: Gastric emptying of a solid/liquid meal (100 g (99m)Tc-minced beef and 150 ml 67Ga-EDTA-labeled water) was measured by scintigraphy on 2 separate days, during hypoglycemia and euglycemia.
Setting: These studies took place at the Department of Nuclear Medicine, Positron Emission Tomography, and Bone Densitometry at the Royal Adelaide Hospital.
Patients: Twenty type 1 patients (4 female, 16 male; age, 45.9 +/- 2.3 yr; duration of known diabetes, 18.0 +/- 2.7 yr) were recruited from outpatient clinics and the Diabetes Centre at the Royal Adelaide Hospital.
Intervention: Hypoglycemia (approximately 2.6 mmol/liter) was established 15 min before and maintained for 45 min after meal consumption. On one of the days, autonomic nerve function was evaluated using cardiovascular reflex tests.
Main outcome measure: The main outcome measure was gastric emptying during hypoglycemia when compared with euglycemia.
Results: Twelve of the 20 subjects had autonomic neuropathy. Gastric emptying of both solid (P < 0.001) and liquid (P < 0.05) was faster during hypoglycemia. The magnitude of this acceleration was greater when the rate of gastric emptying during euglycemia was slower (solid, percentage retention at 100 min, r = -0.52, P < 0.05; liquid, 50% emptying time, r = -0.82, P < 0.0001, but not influenced by autonomic nerve function).
Conclusions: Insulin-induced hypoglycemia accelerates gastric emptying of solids and liquids in long-standing type 1 diabetes, even in those patients with delayed emptying, and is likely to be an important mechanism in the counter-regulation of hypoglycemia.