It is estimated that approximately 30% of patients with diabetes develop diabetic nephropathy. Diabetic nephropathy is a multifactorial progressive disease that occurs through various mechanisms such as hyperglycemia, oxidative stress, inflammation and fibrosis, control or blocking these mechanisms are therefore potential therapeutical targets for this entity. Current treatment options are based on the glycemic control, blood pressure control, as well as the use of medications such as angiotensin-converting enzyme inhibitors and Angiotensin II receptor antagonists, these actions are not enough to stop progression. Pirfenidone is a drug with antifibrotic, antioxidant, and anti-inflammatory properties. Although the specific mechanism is unknown, pirfenidone interferes with the expression, secretion and the effect of the β (TGF-β) transforming growth factor. The investigators plan to carry out a controlled clinical study to evaluate the effect of pirfenidone in patients with type 2 diabetes and nephropathy. The period of time the treatment will be administered will be of 12 months, 62 patients will be included. The primary outcome will be improvement in glomerular filtration rate. The secondary outcomes will be number of patients requiring replacement therapy, 24 hour urine microalbuminuria and change in the concentration of TGF - β. Change in these parameters will be evaluated at the end of the treatment period (12 months). Throughout the study the incidence of adverse events will be recorded, wich will allow us to learn about the safety and security of the drug in this population.