THE RESPONSE OF GASTRIC-INHIBITORY POLYPEPTIDE (GIP) TO ORAL GLUCOSE IN CHRONIC-PANCREATITIS - A STUDY BY RADIOIMMUNOASSAY FOR HUMAN GIP

To investigate the insulinotropic effect of gastric inhibitory polypep tide (GIP) in chronic pancreatitis (CP), we examined the GIP response to 75 g oral glucose in 18 CP patients and 7 normal subjects (controls ) by a radioimmunoassay for human GIP. The GIP response of CP patients was correlated with the pancreatic exocrine function which was evalua ted by the caerulein-secretin test (CS test). Plasma GIP concentration s following the oral administration of glucose were higher in CP patie nts than in controls, but the difference was not significant. When CP patients were divided into 3 groups according to their exocrine dysfun ction (mild, moderate and severe), plasma GIP levels of CP patients wi th severe exocrine dysfunction were significantly higher than those of controls. No correlation was found between the volume and mean bicarb onate concentration and plasma GIP level at 30 min after the glucose i ngestion. Only the amylase output showed a negative correlation with p lasma GIP level. A linear positive correlation was found between the i ntegrated insulin and integrated GIP response's to oral glucose in CP patients with severe exocrine dysfunction, whereas little correlation was observed in those with milder exocrine dysfunction. These data sug gest that in CP patients, endogenous GIP augments the insulin response to oral glucose when pancreatic exocrine insufficiency progresses.