The study will look at the effect of 30 days of treatment of 15 diabetics with proteinuria with N-acetylcysteine ( Mucomyst ) at a dose of 1 gm twice a day by mouth. The primary outcome that will be measured is change in the oxidant stress as measurable by changes in the serum level of isoprostane, Glutathione peroxidase, aconitase and Total oxidant stress. Secondary outcomes measured will be changes in proteinuria and kidney function as measured by spot urine pr/cr and estimated GFR by MDRD formula.