Diabetic Nephropathy Worsens with B-Vitamin Supplementation

High levels of plasma homocysteine are associated with elevated risk for developing diabetic nephropathy, and B vitamins lower homocysteine levels. In a randomized controlled trial, Canadian investigators evaluated pharmacologic doses of combined B-vitamin therapy in 238 adults (75% men; 83% white) with type 1 or type 2 diabetes and known nephropathy; patients with advanced renal failure were excluded. Participants received daily supplements that contained folic acid (2.5 mg), vitamin B₆ (25 mg), and vitamin B₁₂ (1 mg), or placebo. Participants were assessed at baseline and at 18 and 36 months with radionuclide determinations of glomerular filtration rate (GFR). Secondary outcomes included adverse cardiovascular (CV) events such as stroke a…