Comparison of diurnal serum insulin levels during short term treatments with sulfonylurea and with insulin in non-insulin dependent diabetes.

Nine non-insulin dependent type diabetic patients were hospitalized and place on the standard diabetic diet throughout this study period. (25 cal/kg ideal weight/day). After three days of diet therapy alone, 5 mg of glibenclamide was given orally for three days, followed by an interval of four days without medication. 16 units of lente insulin was then administered subcutaneously for three days. The diurnal levels of plasma glucose (PG) and serum immunoreactive insulin (IRI) were determined on the third day of each treatment, and the integrated areas below the curves of the diurnal profile of PG and IRI were compared. The mean fasting PG level before treatment was 200 +/- 21 mg% (mean +/- SE). The initial PG area during diet therapy alone, (4,245 +/- 669 mg . h/dl) decreased significantly to similar levels both by glibenclamide (3, 317 +/- 384 mg . h/dl, P less than 0.05) and by lente insulin (3,177 +/- 552 mg . h/dl, P less than 0.01). The IRI area increased from 187 +/- 24 micromicron . h/ml during diet therapy alone to 296 +/- 65 micromicron . h/ml by glibenclamide (P less than 0.01), and to 267 +/- 43 micromicron . h/ml by lente insulin (P less than 0.05). There was no significant difference between glibenclamide and lente insulin treatments either in PG area or IRI area. These finding suggest that the hypoglycemic effect of glibenclamide treatment in the short term is mainly, if not entirely, due to augmented endogenous insulin secretion.