Association between isolated hypercholesterolemia, isolated hypertriglyceridemia and coronary artery disease in south Indian type 2 diabetic patients

Very high prevalence rates of coronary artery disease have been reported among Indians. The aim of this study was to determine the relative importance of isolated hypercholesterolemia, isolated hypertriglyceridemia, isolated high low-density lipoprotein and isolated low high-density lipoprotein in coronary artery disease among South Indian type 2 diabetic subjects. The study group comprised of 17,885 type 2 diabetic patients attending our institute. A history of documented myocardial infarction was considered as the diagnostic criteria for coronary artery disease. Isolated hypercholesterolemia was defined as serum cholesterol over 200 mg/dL with normal serum triglyceride levels (< or = 200 mg/dL); isolated hypertriglyceridemia was defined as serum triglyceride level over 200 mg/dL with normal serum cholesterol levels (< or = 200 mg/dL). Isolated low high-density lipoprotein was defined as one below 35 mg/dL with normal serum triglyceride levels. Isolated high low-density lipoprotein cholesterol was defined as one over 150 mg/dL with normal serum triglyceride levels. Normolipidemia was defined as serum cholesterol and serum triglyceride both upto 200 mg/dL, high-density lipoprotein 35 mg/dL or above and low-density lipoprotein upto 150 mg/dL. The prevalence of coronary artery disease was significantly high among patients with isolated hypercholesterolemia (4.1%; p < 0.001), isolated high low-density lipoprotein (4.5%; p < 0.001) and isolated low high-density lipoprotein (3.9%; p = 0.005) compared to normolipidemic individuals (2.8%), but not in those with isolated hypertriglyceridemia (3.4%). The odds ratios for coronary artery disease increased with each quartiles of isolated cholesterol, isolated low-density lipoprotein cholesterol and total cholesterol to high-density lipoprotein ratio and reached statistical significance in the last quartile (p < 0.05). There was no significant increase in the odds ratios for coronary artery disease in relation to quartiles of isolated triglycerides. For isolated low high-density lipoprotein, when the last quartile was taken as the reference, the odds ratio for coronary artery disease in the first quartile reached statistical significance (p = 0.03). Multivariate regression analysis revealed age (odds ratio 1.06; p < 0.001), male sex (odds ratio 1.7; p < 0.001), hypercholesterolemia (odds ratio 1.26; p = 0.07) and high low-density lipoprotein levels (odds ratio 1.22; p = 0.043) to be strongly associated with coronary artery disease. Among South Indian type 2 diabetic subjects, serum isolated hypercholesterolemia and high low-density lipoprotein cholesterol but not isolated hypertriglyceridemia appear to be associated with coronary artery disease.