Effect of statins on total cholesterol concentrations and cardiovascular outcomes in patients with diabetes mellitus: a population-based cohort study

In the UK, clinicians usually make treatment decisions based on total cholesterol (TC) at the same time supplemented with high-density lipoprotein cholesterol (HDL-C) measurements. We evaluated statin-associated TC concentration change and its impact on cardiovascular (CV) risk reduction in diabetic patients in the setting of usual care. In a population-based cohort study using a record-linkage database in Tayside, Scotland. we studied 6,697 diabetic patients who had at least two separate TC measurements between 1993 and 2007. Patients were categorized into statin-exposed and statin-unexposed groups according to statin use status during the follow-up. The main outcomes were TC concentration change from baseline, CV events, and all-cause mortality during the follow-up. Multivariate Cox regression models with a time-dependent variable for statins were employed to assess outcome risk. Statin-associated TC concentrations decreased by 1.64 mmol/L (28%) in patients without CV disease (CVD) (5,984) and 1.19 mmol/L (23%) in patients with CVD (713) from 5.90 mmol/L and 5.20 mmol/L at baselines, respectively. Statin use reduced incident and recurrent CV events by 39% and 41%, respectively [adjusted hazard ratio (HR) 0.61, 95% confidence interval (CI) 0.57-0.66; 0.59 95% CI 0.47-0.76) per millimole of TC reduction. For all-cause mortality, the adjusted HRs were 0.39 (95% CI 0.32-0.47) in primary prevention and 0.58 (95% CI 0.42-0.80) in secondary prevention. Statin use was as effective in diabetic patients in the setting of usual care, as in the clinical trials, in both primary and secondary prevention. TC changes can be used as a measure of statin efficacy in the absence of low-density lipoprotein cholesterol (LDL-C) in diabetic patients.