Association of methylene tetrahydrofolate reductase C677T genotype with type 2 diabetes mellitus patients with and without renal complications.

Diabetes is gradually getting the status of a global epidemic, with India projected as the capital of type 2 diabetes mellitus (T2DM). Nephropathy is an important complication of diabetes and a major cause of end-stage renal disease. Studies from different parts of the world have given controversial results regarding the association of methylene tetrahydrofolate reductase (MTHFR) gene variation with T2DM and diabetic nephropathy (DN). This case-control study assessed the association of MTHFR C677T mutation in T2DM and DN cases. Genotyping of MTHFR was carried out for 236 T2DM cases with diabetes diagnosed for >8 years, having either normoalbuminuria (n=100) or established DN (n=136). One hundred age- and sex-matched healthy individuals with normal blood sugars and no family history of T2DM were selected as controls. This first report from India gives a highly significant odds ratio of 4.0423 (95% confidence interval=1.8753-8.7133), indicating that the MTHFR 677T allele confers a fourfold risk of developing DM in our population. The frequency of the T allele in both the DM and DN groups was similar (i.e., 0.16 and 0.11, respectively), showing no association with the initiation or progression of DN. Individuals with a family history of diabetes or with risk factors such as obesity, hypertension, and impaired glucose tolerance should be screened for MTHFR C677T mutation and may be prescribed folic acid, vitamin B6, and vitamin B12 to assess if this helps in delaying the onset of diabetes.