Chronic alcoholic pancreatitis (CAP) is often complicated by the onset of diabetes mellitus. The aim of this study was to assess the residual beta cell function (evaluated by means of the glucagon test) and the mean disposal rate of insulin (with the insulin tolerance test) in 66 CAP patients with or without abnormalities of glucose metabolism and in 19 control subjects. On the basis of our data, we conclude that the glucose metabolism abnormalities in chronic pancreatitis occurs as a result not merely of impaired production of endogenous insulin, but also as result of a combination of the latter together with insulin resistance.