Effect of troglitazone on urinary albumin excretion and serum type IV collagen concentrations in Type 2 diabetic patients with microalbuminuria or macroalbuminuria.

AIMS: Troglitazone, a newly developed thiazolidinedione derivative, has been shown to ameliorate microalbuminuria in diabetic animal model and in human diabetic nephropathy in short-term studies. The aim of the present study was to determine whether troglitazone or sulphonylurea affect micro- albuminuria, macroalbuminuria, or serum type IV collagen concentrations in patients with diabetic nephropathy. METHODS: We studied 32 normotensive patients with type 2 diabetes mellitus associated with microalbuminuria (n = 16) or macroalbuminuria (n = 16) and 20 healthy controls. The patients were randomly assigned to one of two groups: those treated with glibenclamide (5.0 mg/day) (n = 8) and those treated with troglitazone (400 mg/day) (n = 8). They received the drug regimen for 12 months. Serum type IV collagen was measured with sandwich enzyme immunoassay. RESULTS: Type IV collagen concentrations in macroalbuminuric patients were higher than those in microalbuminuric patients (P < 0.05) and healthy controls (P < 0.01). Troglitazone reduced urinary albumin excretion (UAE) in micro-albuminuric patients from 126 microg/min (range 58--180 microg/min) to 42 microg/min (range 14--80 microg/min) (P < 0.01) and also reduced serum type IV collagen levels gradually at 3, 6 and 12 months after treatment (P < 0.05). However, glibenclamide did not affect UAE and type IV collagen levels in micro- albuminuric diabetes patients. In addition, neither troglitazone nor gliben- clamide changed UAE and type IV collagen levels in macroalbuminuric patients. CONCLUSIONS: These data suggest that troglitazone is an effective treatment for renal injury in patients with early diabetic nephropathy.