No effect of gliclazide on gastric inhibitory polypeptide (GIP) in type II diabetes

Seven subjects with non-insulin-dependent diabetes mellitus were studied prior to and after 1 month of treatment with gliclazide, 80 mg twice daily. Individuals attended for a standard breakfast test meal (10 kcal/kg) on three occasions--prior to therapy, first day of therapy, and 30th day of therapy. Blood samples were collected between 0 and 240 min post-prandially and assayed for glucose, insulin, C-peptide, glucagon, pancreatic polypeptide, gastric inhibitory polypeptide (GIP), and gastrin. Following gliclazide, fasting and post-prandial glucose levels were significantly improved. An increase in post-prandial insulin and C-peptide levels was noted on the first treatment day and values remained elevated for the study period. GIP and other measured peptide hormones were unchanged. These data suggest that gliclazide asserts its hypoglycaemic effects by promoting insulin release, and has no detectable effect on other enteropancreatic hormones.