Objective: To determine the prevalence of Diabetic Nephropathy (DN) in patients with type 2 Diabetes Mellitus (T2DM) with over 5 years of evolution in rural communities of Guanajuato, Mexico, and evaluate the effects of an ARB treatment over 6 months in patients with DN. Materials and methods: Patients of both sexes, 38–86 years, T2DM over 5 years of evolution and diagnosed with arterial hypertension (HT) after T2DM incidence. Monthly determination of microalbuminuria (MA), lipids, glucose, serum creatinine, and glycated hemoglobin (HbA1c). Estimated glomerular filtration rate (eGFR) by the Modification of Diet in Renal Disease (MDRD) formula. A dose of 80 mg of Telmisartan was administered daily over 6 months. Results: The total adult population of two rural communities (3609 subjects) was studied, 335 subjects had T2DM, among them 80 (with a prevalence of 24%) had DN and HT. Sixty-seven patients received Telmisartan, and showed significant improvement in all parameters studied. Conclusions: A higher prevalence of DN than that reported in the Mexican National Health Survey (ENSANUT) was found. Further research is required in a larger population sample in order to confirm the results of Telmisartan treatment.