EFFECT OF HYPERGLYCEMIA ON GASTRIC-ACID SECRETION DURING THE GASTRIC PHASE OF DIGESTION

We have examined the effect of an acute stable hyperglycemia on gastri c acid secretion during the gastric phase of digestion. Gastric acid o utput was measured with a recovery marker (phenol red) under basal con ditions and after repeated intragastric instillation of a Liquid meal in seven healthy subjects on two separate occasions: during normoglyce mia (serum glucose, 5 mM) and during acute hyperglycemia (serum glucos e, 15 mM). Premeal gastric acid output was significantly (P < 0.05) re duced during hyperglycemia compared with during normoglycemia (2.6 +/- 1.0 vs. 5.8 +/- 1.8 mmol/h). Intragastric meal-stimulated incremental acid output during hyperglycemia was significantly (P < 0.05) reduced compared with during normoglycemia (19 +/- 4 vs. 38 +/- 9 mmol/120 mi n). Meal-stimulated gastrin release during hyperglycemia was significa ntly (P < 0.05) reduced compared with that during normoglycemia (4.9 /- 1.3 vs. 6.6 +/- 1.6 mu g.l(-1).120 min(-1)). The intragastric meal induced significant (P < 0.05) increases in pancreatic polypeptide con centrations only during normoglycemia. During hyperglycemia, recovery rates of gastric contents were significantly (P < 0.05) increased comp ared with during normoglycemia, both before (81 +/- 4 vs. 71 +/- 6%) a nd after (72 +/- 4 vs. 57 +/- 4%) meal ingestion, pointing to delayed gastric emptying of liquids during hyperglycemia. In conclusion, 1) ga stric acid secretion under unstimulated conditions and during the gast ric phase of digestion is reduced during hyperglycemia; 2) meal-stimul ated gastrin release is significantly reduced during hyperglycemia; 3) the reduction in meal-stimulated acid output is correlated with the r eduction in gastrin release; and 4) pancreatic polypeptide secretion i s significantly reduced during hyperglycemia, pointing to impaired vag al cholinergic tone.