Effect of pioglitazone on urinary liver-type fatty acid-binding protein concentrations in diabetes patients with microalbuminuria

BACKGROUND: Urinary liver-type fatty acid-binding protein (L-FABP) is a useful marker for renal tubulointerstitial injury. Pioglitazone is reported to be effective in early diabetic nephropathy. The aim of the present study was to determine whether pioglitazone affects urinary L-FABP levels in diabetic nephropathy patients with microalbuminuria. METHODS: Sixty-eight patients with type 2 diabetes and microalbuminuria were randomized to a 12-month treatment with pioglitazone (30 mg/d, n = 17), glibenclamide (5 mg/d, n = 18), voglibose (0.6 mg/d, n = 17), or nateglinide (270 mg/d, n = 16). Pre- and posttreatment urinary albumin excretion (UAE) and urinary L-FABP concentrations were compared between the four treatment groups and 40 age-matched healthy subjects. RESULTS: Pretreatment UAE and urinary L-FABP levels differed little between the four groups. UAE and urinary L-FABP levels were significantly greater in the diabetes patients than in the healthy subjects (UAE: p < 0.001; L-FABP: p < 0.01). After 6 and 12 months, UAE and urinary L-FABP were significantly lower in the pioglitazone treatment group than in the other treatment groups (UAE: 6 months, p < 0.01 and 12 months, p < 0.001; L-FABP: 6 months, p < 0.05 and 12 months, p < 0.01). CONCLUSIONS: Pioglitazone, but not glibenclamide, voglibose, or nateglinide, appears to be effective in reducing UAE and the urinary L-FABP level, suggesting that pioglitazone has a specific role in ameliorating both glomerular and tubulointerstitial lesions associated with early diabetic nephropathy.