We studied the effect of troglitazone, a new oral antidiabetic agent that potentiates insulin action and reduces insulin resistance, on albuminuria in streptozotocin (STZ)-treated diabetic rats. Without affecting blood glucose level, blood pressure, and creatinine clearance, troglitazone treatment of diabetic rats significantly decreased the diabetes-associated albuminuria at all time points studied 14 to 12 weeks of treatment: diabetic 510 +/- 161 micrograms/24 h v diabetic treated 112 +/- 34 micrograms/24 h at 12 weeks, P < .05). These data suggest that troglitazone has potential in the treatment of diabetic nephropathy.