The development of diabetic nephropathy has been linked to several genetic polymorphisms, including those related with homocysteine metabolism such as the methylenetetrahydrofolate reductase (MTHFR)and the cystathionine-beta-synthase genes. Such alterations are associated with hyperhomocysteinemia, which is a known independent risk factor for the development of endothelial dysfunction and cardiovascular disease.

In the Mexican population there is a high prevalence of the C677T MTHFR mutation. The investigators performed this study to evaluate the prevalence of this polymorphism in type 2 diabetic patients with diabetic nephropathy compared with type 2 diabetic patients without nephropathy, besides evaluating the relationship of hyperhomocysteinemia with endothelial dysfunction and microalbuminuria before and after the administration of folic acid. We proposed that the endothelial dysfunction caused by the hyperhomocysteinemia could be reversed after the administration of folic acid.

Inclusion Criteria:

• Type 2 diabetes mellitus patients with 5 to 15 years of diagnosis
• Microalbuminuria (defined as a urinary albumin/creatinine ratio between 30 and 300 mg/g)
• A1c less than 9% in the last year

Exclusion Criteria:

• Acute diabetic complications
• A1c greater than 9% in the last year
• Acute infectious process
• Hepatic disease
• Thyroid disease