COMBINATION OF INSULIN WITH GLIPIZIDE INCREASES PERIPHERAL GLUCOSE DISPOSAL IN SECONDARY FAILURE TYPE-2 DIABETIC-PATIENTS

Twenty Type 2 diabetic patients, recently converted to insulin because of inadequate control on oral hypoglycaemic agents, were studied. Endogenous insulin reserve was measured by glucagon stimulation, and insulin‐mediated peripheral glucose disposal by a hyperglycaemic (11 mmol I−1) clamp, measurements being repeated after 8 weeks of glipizide or placebo therapy in addition to the patients' usual insulin. The study was randomized and double blind. Fasting and stimulated C‐peptide levels did not change on glipizide or placebo. Insulin‐mediated glucose disposal rose from 2.5 (1.5–8.0) (median (range)) to 4.2 (2.3–8.4) mg kg−1 min−1 in the glipizide group (n = 9, p < 0.01), but did not change in the placebo group. Glycosylated haemoglobin did not change in either group, but median fasting plasma glucose fell from 10.6 (6.1–15.1) to 9.0 (6.4–11.2) mmol I−1 in the glipizide group (p<0.02). Fasting insulin rose on glipizide from 10.1 (4.0–23.2) to 13.0 (6.4–33.8) mU I−1 (p < 0.02). Insulin dosage fell in the glipizide group from 36 to 26 U day−1, as 4 patients experienced hypoglycaemic symptoms. HDL‐Cholesterol fell in all patients on glipizide, from 0.94 (0.79‐2.13) to 0.79 (0.62‐1.95) mmol I−1 (p < 0.01). Combination of insulin with the sulphonylurea glipizide in secondary failure Type 2 diabetic patients leads to increased insulin‐mediated peripheral glucose disposal. Glipizide may have an adverse effect on HDL‐cholesterol, which is unrelated to change in diabetic control. 1990 Diabetes UK