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

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.