Pancreatic glucagon secretion and exocrine function (BT-PABA test) in chronic pancreatitis

Plasma concentrations of pancreatic glucagon, C-peptide, and pancreatic polypeptide were measured during arginine stimulation in 16 patients with chronic pancreatitis, in eight subjects with idiopathic diabetes mellitus, and in seven healthy controls. The hormone responses were compared with exocrine pancreatic function as assessed using the urinary excretion rate of p-aminobenzoic acid after oral ingestion of n-benzoyl-l-tyrosyl-p-aminobenzoic acid (BT-PABA). The increase in pancreatic glucagon levels during arginine stimulation was significantly reduced in patients with chronic pancreatitis compared to healthy controls, most markedly in those with secondary diabetes. In contrast, the glucagon response was unimpaired in patients with idiopathic diabetes. The arginine-induced increase in plasma glucagon and C-peptide concentrations correlated significantly with urinary PABA excretion in chronic pancreatitis (P less than 0.001, P less than 0.01, respectively). The responses of plasma C-peptide and pancreatic polypeptide separated pancreatitic and idiopathic diabetes less well. Thus, the glucagon response to arginine distinguished secondary diabetes due to chronic pancreatitis and idiopathic diabetes mellitus. The correlation between urinary PABA excretion and glucagon levels suggests that in chronic pancreatitis there is a parallel impairment of exocrine and endocrine function.