Pharmacologic lipid-lowering therapy in type 2 diabetes mellitus: background paper for the American College of Physicians

Abstract

Background: Cardiovascular disease is the primary complication and cause of death in patients with type 2 diabetes mellitus. Modification of cardiovascular risk factors may improve patient outcomes.

Purpose: To evaluate the effectiveness of pharmacologic lipid-lowering therapy on outcomes in type 2 diabetes mellitus.

Data sources: Review of the literature.

Study selection: Randomized trials evaluating clinical outcomes of lipid-lowering treatment in patients with diabetes.

Data extraction: Studies were identified by searching the Cochrane Library, MEDLINE, meta-analyses, review articles, and inquiries to experts. The Cochrane Library and MEDLINE searches were done in September 2002. Data were abstracted onto standardized forms by a single reviewer and were confirmed by a second reviewer.

Data synthesis: Meta-analysis of 6 primary prevention studies showed that lipid-lowering medications reduced risks for cardiovascular outcomes (relative risk, 0.78 [95% CI, 0.67 to 0.89]; absolute risk reduction, 0.03 [CI, 0.01 to 0.04] in 4.3 years of treatment); 1 major cardiovascular event was prevented by treating 34 to 35 patients. Meta-analysis of 8 studies of secondary prevention showed a similar relative risk (0.76 [CI, 0.59 to 0.93]) but more than twice the absolute risk reduction (0.07 [CI, 0.03 to 0.12] in 4.9 years of treatment) and a number needed to treat for benefit of 13 to 14. Most studies compared a lipid-lowering drug with placebo but did not evaluate the effect of reaching specific cholesterol levels. The benefit of lipid lowering with a fixed dose of a statin appeared to be similar regardless of starting cholesterol levels.

Limitations: Target cholesterol levels and the effectiveness of dose titration (or the use of multiple agents) have not been rigorously examined.

Conclusions: In patients with type 2 diabetes, treatment with lipid-lowering agents reduces cardiovascular risk. Most patients, including those whose baseline low-density lipoprotein cholesterol levels are below 2.97 mmol/L (<115 mg/dL), and possibly below 2.59 mmol/L (<100 mg/dL), benefit from statins. Moderate doses of these drugs suffice in most patients with diabetes.