Individuals with the haplotype AAG (PPARGC1A gene) and CTCG (UCP1 gene) have increased susceptibility to IFG or T2DM, while those with haplotype AAG (PPARGC1A gene) and CTCA (UCP1 gene) have a lower risk of IFG or T2DM. This evidence concerns the gene UCP1 and type 2 diabetes mellitus.