The present invention discloses genes, SNP markers and haplotypes of susceptibility or predisposition to obesity, type 2 diabetes (T2D) and subdiagnosis of obesity and T2D and related medical conditions. Particularly, the present invention provides T2D and obesity associated markers from gene SUCLA2. Methods for diagnosis, prediction of clinical course and efficacy of treatments for T2D, obesity and related phenotypes using polymorphisms in the risk genes and other related biomarkers are also disclosed. Kits are also provided for the diagnosis, selecting treatment and assessing prognosis of obesity and T2D.
