Circulating homocysteine levels in patients with type 2 diabetes mellitus.
BACKGROUND AND AIM: Previous studies have shown conflicting results regarding circulating homocysteine levels in patients with type 2 diabetes. METHODS AND RESULTS: This observational study included 2121 patients with angiographically proven coronary artery disease (507 patients with type 2 diabetes and 1614 patients without diabetes). Circulating homocysteine levels, methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism, renal function, presence of coronary artery disease (CAD) diagnosed by coronary angiography, and circulating folate and vitamin B12 status were assessed. Plasma homocysteine levels [median (25th; 75th percentile)] were significantly higher in patients with diabetes than in those without [12.4 micromol/L (9.9 micromol/L; 15.9 micromol/L) versus 11.7 micromol/L (9.6 micromol/L; 14.5 micromol/L), P=0.011]. Diabetes affected homocysteine levels only in patients with a glomerular filtration rate<90 mL/min [13.0 micromol/L (10.5 micromol/L; 16.7 micromol/L) in patients with diabetes versus 12.2 micromol/L (10.1 micromol/L; 15.2 micromol/L) in patients without diabetes, P=0.006] but not in those with a glomerular filtration rate> or = 90 mL/min [10.1 micromol/L (8.1 micromol/L; 12.4 micromol/L) versus 10.2 micromol/L (8.8 micromol/L; 12.3 micromol/L), P=0.267]. Multivariable analysis did not show an independent association between diabetes and homocysteine level (P=0.342). CONCLUSION: Circulating homocysteine levels are increased in patients with type 2 diabetes compared with non-diabetic patients due to a more diabetes-associated adverse risk profile rather than to diabetes itself.