Effect of long-term administration of insulin and glibenclamide on pancreatic A and B cell function

To investigate the effects of insulin and sulfonylurea drug administration on islet A and B-cell functions, insulin and glucagon response was studied in normal rats treated with insulin (4 U/day subcutaneously) or glibenclamide (0.03 mg/kg intraperitoneally) for 8 weeks. In intravenous glucose tolerance test (0.5 g/kg), lower insulin response and impaired glucose tolerance were observed in insulin-treated rats and higher insulin response and impaired glucose tolerance were observed in glibenclamide-treated rats. In perfused pancreas, insulin response to glucose and arginine was significantly lower in insulin-treated rats and that was significantly higher in glibenclamide-treated rats. Glucagon response was not altered by insulin or glibenclamide treatment. These results suggest that hyperinsulinisation and glibenclamide administration strongly influence pancreatic B-cell function but not influence pancreatic A-cell function.