UCP3 and type 2 diabetes mellitus: Over the past few decades, numerous studies have investigated the association between single-nucleotide polymorphisms (SNPs) of the UCP1-3 genes and T2DM susceptibility, and the most focused on the -3826A/G (rs1800592) polymorphism in the promoter region of the UCP1 gene, the -866G/A (rs659366) polymorphism in the promoter region and a missense variant in exon 4 (Ala55Val, C/T, rs660339) of the UCP2 gene, and the -55C/T (rs1800849) polymorphism in the promoter region of the UCP3 gene [18–21].