To assess in diabetic patients with coronary heart disease (CHD) the effect of cholesterol lowering with simvastatin on mortality and the risk of CHD and other atherosclerotic events.
A post hoc subgroup analysis was carried out on data from 202 diabetic patients and 4,242 nondiabetic patients with previous myocardial infarction or angina pectoris, serum total cholesterol 5.5–8.0 mmol/l, and serum triglycerides ≤ 2.5 mmol/l who were participating in the Scandinavian Simvastatin Survival Study (4S). Participants in the 4S were randomly assigned to double-blind treatment with simvastatin, 20 mg daily, with blinded dosage titration up to 40 mg daily, according to cholesterol response during the first 6–18 weeks, or placebo. Endpoints were 1) total mortality, 2) major CHD events (CHD death or nonfatal myocardial infarction), 3) other acute atherosclerotic events, 4) myocardial revascularization procedures.
Over the 5.4-year median follow-up period, simvastatin treatment produced mean changes in serum lipids in diabetic patients similar to those observed in nondiabetic patients. The relative risks (RRs) of main endpoints in simvastatin-treated diabetic patients were as follows: total mortality 0.57 (95% CI, 0.30–1.08; P = 0.087), major CHD events 0.45 (95% CI, 0.27–0.74; P = 0.002), and any atherosclerotic event 0.63 (95% CI, 0.43–0.92; P = 0.018). The corresponding RRs in nondiabetic patients were the following: 0.71 (95% CI, 0.58–0.87; P = 0.001), 0.68 (95% CI, 0.60–0.77; P < 0.0001), and 0.74 (95% CI, 0.68–0.82; P < 0.0001).
The results strongly suggest that cholesterol lowering with simvastatin improves the prognosis of diabetic patients with CHD. The absolute clinical benefit achieved by cholesterol lowering may be greater in diabetic than in nondiabetic patients with CHD because diabetic patients have a higher absolute risk of recurrent CHD events and other atherosclerotic events.