The aim of the present study was to ascertain whether secretory capacity of the pancreas, evaluated by assaying serum total amylase (TA) and pancreatic amylase activity (PA) and fecal chymotrypsin excretion (FCT), is impaired in diabetic and to what extent it is influenced by the degree of glyco-metabolic control. TA, PA and FCT were assayed in 40 patients affected with type II diabetes mellitus in secondary insufficiency, both at hospitalization and after metabolic control assessment; 43 hospitalized patients constituted the control group. A statistically significant difference was found between the metabolic failure phase values of diabetics patients and those of the control group for TA (p less than 0.0005), PA (p less than 0.025) and FCT (p less than 0.0005); between metabolic control phase values and control group fo TA (p less than 0.0005), and FCT (p less than 0.005) but not for PA values. PA values were statistically significant, within diabetic group, before and after metabolic control assessment. A statistically significant result was obtained by correlating C-peptide and FCT values (p less than 0.01), C-peptide and PA values (p less than 0.001); glycaemia and PA values (p less than 0.05). Our data suggest that in diabetic patients there is an impairment in secretory capacity of the pancreas and that the the PA is the more sensitive enzyme to the local levels of insulin.