Support for a protective effect of bilirubin on diabetic nephropathy in humans

To the Editor: We read with great interest the article by Fujii et al.1 in which they found that bilirubin (BIL) may protect against diabetic nephropathy (DN) in experimental animals, which could pave the way for novel antioxidant therapies for DN. Given these tantalizing results in animal models, it would be of interest to see whether BIL also exerts protection against DN in humans. To this end, we investigated the association between BIL and DN in a case–control study. Cases of DN were defined as duration of type 2 diabetes >5 years, albuminuria >300 mg per day, and presence of diabetic retinopathy (n=32). Controls were type 2 diabetic patients without nephropathy, matched for age, sex, and duration of diabetes (n=32). Age was 64±9 years, 54% were male, and median (interquartile range, IQR) duration of diabetes was 15 (10–20) years. Urinary albumin concentration was 752 (239–1074) mg/l in cases versus 3 (3–6) mg/l in controls (P