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 w as to determine whether troglitazone or sulphonylurea affect microalbuminur ia, macroalbuminuria, or serum type IV collagen concentrations in patients with diabetic nephropathy. Methods We studied 32 normotensive patients with type 2 diabetes mellitus a ssociated with microalbuminuria (n = 16) or macroalbuminuria (n = 16) and 2 0 healthy controls. The patients were randomly assigned to one of two group s: 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 immunoa ssay. Results Type IV collagen concentrations in macroalbuminuric patients were h igher than those in microalbuminuric patients (P < 0.05) and healthy contro ls (P < 0.01). Troglitazone reduced urinary albumin excretion (UAE) in micr oalbuminuric patients from 126 mug/min (range 58-180 mug/min) to 42 mug/min (range 14-80 mug/min) (P < 0.01) and also reduced serum type IV collagen l evels gradually at 3, 6 and 12 months after treatment (P < 0.05). However, glibenclamide did not affect UAE and type IV collagen levels in microalbumi nuric diabetes patients. In addition, neither troglitazone nor glibenclamid e 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.