Cardiovascular disease (CVD) is a leading cause of all deaths worldwide, accounting for 31% of deaths (17.5 million deaths) per year in 2012 [2]. In Korea, CVD is also one of the leading causes of death, accounting for 19% of deaths per year in 2015 [3]. CVD can be prevented by comprehensive management of risk factors including diabetes mellitus, hypertension, dyslipidemia, and smoking [4]. Notably, statin treatment to reduce the level of low density lipoprotein cholesterol (LDL-C) has reduced the rate of morbidity and mortality associated with CVD. Therefore, statin therapy was the mainstay of treatment for both primary and secondary CVD prevention. Since the 2013 American College of Cardiology (ACC) and American Heart Association (AHA) guidelines were published, there have been many debates and discussions on the issue of whether to set a therapeutic target level of LDL-C concentration or to recommend a specific intensity statin regardless of LDL-C levels. In addition, in the case of the Korean population, it is necessary to confirm whether the CVD risk prediction model, i.e., the pooled cohort equation used in the ACC/AHA guidelines, would also be suitable for the Korean population and whether the effect of statin treatment would be similar to Caucasians.

As several previous studies have reported [567], we also observed that moderate-intensity statins were more effective in Korean patients with type 2 diabetes mellitus (T2DM) than in Caucasians. We agree with Dr. Jeon's opinion that we may have to reclassify statin intensities according to LDL-C lowering efficacy in the Korean population. In particular, rosuvastatin had a considerably greater LDL-C lowering effect in our study (51.6% reduction of LDL-C with 5 mg of rosuvastatin and 56% reduction with 10 mg of rosuvastatin) than in Caucasian populations. This finding was consistent with those of other previous studies [7]. Such a high efficacy could be associated with high plasma levels of rosuvastatin and its metabolites such as N-desmethyl rosuvastatin and rosuvastatin-lactone in Asians, which are partly due to genetic polymorphisms influencing hepatic clearance of the enzyme CYP2C9 [68]. Therefore, low dose rosuvastatin could be cost-effective in Asian populations including Korea; however, adverse effects would be similar among Koreans and Caucasians depending on plasma levels (and efficacies) despite the lower dose.

Depending on whether we recommend reducing LDL-C levels by 30% to 50% from baseline or reducing LDL-C concentrations below 100 mg/dL, moderate-intensity statins could be a mainstay of treatment for managing dyslipidemia in Korean patients with T2DM. If the percent reduction is a priority, we can recommend low-intensity statins to 40- to 75-year-old Korean patients with T2DM for primary prevention. However, before we recommend low-intensity statins, we have to consider whether it will be enough to reduce the incidence of CVD events in a high-risk population. Hence, more concrete evidence is required to develop Korean guidelines for the management of dyslipidemia; therefore, further research is warranted to elucidate the adequate intensity and type of statins that could reduce actual CVD events instead of LDL-C lowering efficacy in the Korean population.