Human pancreatic polypeptide secretion in conditions of exogenous and endogenous hyperglycaemia.

The effects of exogenous and endogenous hyperglycaemia on human pancreatic polypeptide secretion have been studied. In normal subjects elevation of plasma glucose concentration by glucose infusion both depressed the basal levels of circulating human pancreatic polypeptide (by 40-50%) and consistently reduced the human pancreatic polypeptide response to the ingestion of a portion-rich meal (areas above pre-meal value: 19.5 +/- 4.1 (mean +/- SEM) vs. 9.6 +/- 2.1, p < 0.01) as well as to caerulein infusion (areas above pre-caerulein value: 8.8 +/- 2.2 vs. 4.6 +/- 1.4, P < 0.01). In diabetic subjects treated with sulphonylureas or diet (fasting plasma glucose: 166 +/- 11 mg/dl, n = 24), human pancreatic polypeptide secretion evoked by food was similar to that of 24 healthy individuals (areas above basal value: 46.6 +/- 9.9 and 33.6 +/- 3.6, respectively). In insulin dependent diabetics (fasting plasma glucose: 231 +/- 19 mg/dl, n = 21) the human pancreatic polypeptide response to the meal (area above basal value: 78.2 +/- 13.7) was significantly greater than that of the controls as well as that of the noninsulin-dependent group (P < 0.05). Since the administration of pancreatic polypeptide to man has been shown to decrease pancreatic exocrine output, postprandial human pancreatic polypeptide hypersection may contribute to the decreased exocrin function of the pancreas often found in insulin-dependent diabetics.