Diabetic kidney disease is the leading cause of new cases of kidney failure in the United States. In the kidneys of diabetic patients, there is accumulation of protein that leads to the formation of scar tissue and poor kidney function. Because of this many patients eventually require dialysis or kidney transplantation. A new investigational drug, pirfenidone, has been shown to be beneficial in a number of diseases in which scar formation leads to disease progression. It is our goal to examine whether pirfenidone is effective at stabilizing or reducing progressive diabetic kidney dysfunction.