Comparison of lipid profiles and lipoprotein a levels in patients with type 2 diabetes mellitus during oral hypoglycemic or insulin therapy

OBJECTIVE: The aim of this study is to compare lipid and lipoprotein (a) profiles in patients with type 2 diabetes mellitus (DM) on insulin and oral hypoglycemic therapy.

METHODS: The study took place in the Department of Physiology, Army Medical College, Rawalpindi, Pakistan, during 2002. Ninety-seven type 2 DM patients participated in the study. We divided the patients according to the type of treatment into sulphonylurea (n=40), sulphonylurea plus metformin (n=33) and insulin (n=24) therapy groups as well as 40 healthy subjects served as controls. Fasting blood samples were analyzed for lipoprotein (a) [Lp (a)], total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), glucose, glycosylated hemoglobin (HbA1c) and insulin.

RESULTS: Different groups of diabetic patients showed elevated fasting blood glucose (FPG) levels (p<0.0001 for all), HbA1c (p<0.0001 for all) compared with controls. Meanwhile, fasting insulin levels were elevated only in insulin treated group compared with oral hypoglycemic treated groups and controls (p<0.0001 for all). Patients on sulphonylurea and on sulphonylurea plus metformin groups showed significantly elevated TC (p<0.001, p<0.0001), TG (p<0.001, p<0.01), LDL-C (p<0.01, p<0.001) and LDL-C/HDL-C (p<0.0001, p<0.0001) compared with controls. Insulin therapy group showed significantly decreased TC, TG, LDL-C, LDL-C/HDL-C levels compared with sulphonylurea and sulphonylurea plus metformin treated groups, however, no significant difference was noted in the levels of above mentioned parameters and controls. Meanwhile, HDL-C levels were significantly lower in all diabetic groups compared with controls and were higher in insulin treated group compared with sulphonylurea plus metformin therapy group (p<0.05). Lipoprotein (a) levels were significantly higher in different diabetic groups compared with controls. While there was a non-significant difference in Lp (a) levels between different diabetic groups.

CONCLUSION: Patients with type 2 DM who are being treated on insulin have a better lipid profile (TC, HDL-C, LDL-C, TG) compared with those patients on oral hypoglycemic agents. Meanwhile, Lp (a) levels were raised in all diabetic patients and seem not to be affected either by insulin or by oral hypoglycemic treatment.