Joint role of non-HDL cholesterol and glycated haemoglobin in predicting future coronary heart disease events among women with type 2 diabetes

Aims/hypothesis. Non-HDL cholesterol (the sum of LDL, VLDL and IDL cholesterol) is considered to be particularly valuable in the management of dyslipidaemia in type 2 diabetes. However, it remains uncertain whether the association between non-HDL cholesterol and cardiovascular risk in type 2 diabetes depends on the status of hyperglycaemia. We aimed to determine whether non-HDL cholesterol predicts CHD events among diabetic women independently of currently established risk factors and the status of glycaemic control. Methods. We prospectively followed 921 diabetic women in the Nurses' Health Study, who were free of cardiovascular disease at the time that blood was drawn in 1989/90. During 10 years of follow-up, we identified 122 incident CHD cases. Results. After adjustment for age, BMI, smoking, alcohol consumption, and other lifestyle risk factors, the multivariate relative risks (RRs) of CHD for extreme quartiles were 1.97 (95% CI: 1.14-3.43) for non-HDL cholesterol, 1.78 (1.02-3.11) for apolipoprotein B-100, and 1.93 (1.15-3.22) for LDL cholesterol. However, the association between non-HDL cholesterol and CHD risk was only apparent among women with elevated fasting triglycerides (RR for extreme quartiles: 3.80; p=0.045). HbA₁c was strongly associated with increased CHD risk (RR for increase by 1 unit: 1.24; 95% CI: 1.13-1.35), and both non-HDL cholesterol and HbA₁c additively predicted CHD risk (RR for the combination of high non-HDL cholesterol and high HbA ₁c[tertiles]: 4.59). Conclusions/interpretation. Our study suggests that non-HDL cholesterol and HbA₁c are potent predictors of CHD risk in diabetic women. Therapies to lower CHD risk in diabetic patients should emphasise both glycaemic control and lipid lowering.