Impact of Severe Hypercholesterolemia on Cardiovascular Risk in Individuals With or Without Diabetes Mellitus

OBJECTIVE: The aim of the current study was to investigate whether the impact of low-density lipoprotein-cholesterol (LDL-C) levels on cardiovascular risk is different between individuals with severe hypercholesterolemia and diabetes mellitus (DM) and those without DM. METHODS: This study used the database of a National Health Insurance Service cohort of Korea. Among individuals who underwent health check-up, 2,261,332 were included and categorized into 3 groups with severe hypercholesterolemia, >260, 225–259, and 190–224 mg/dL groups, and a control group (<160 mg/dL). Risks of composite events (myocardial infarction [MI], coronary revascularization, and ischemic stroke) and total mortality were analyzed, according to the presence of DM. RESULTS: Of the study population, 5.2% had DM. During median follow-up of 6.1 years, the rates of composite events (/1,000 person-year) in non-DM and DM subjects were up to 5.66 and 8.92, respectively. Adjusted hazard ratios (aHRs) of the composite events ranged up to 3.11 and 1.44 in non-DM and DM groups, respectively (p<0.0001 between LDL-C categories in both groups). Dependency of aHR on LDL-C levels was more prominent in the non-DM group. aHRs of MI and coronary revascularization showed similar tendency to the composite events. Although aHRs of ischemic stroke (p<0.0001) and total mortality (p=0.002) were different according to LDL-C categories in the non-DM group, these relations were not observed in DM group. CONCLUSION: Although individuals with severe hypercholesterolemia had high cardiovascular risk when DM was present, the impact of LDL-C on the risk was attenuated in this population.