TCF7L2 and diabetes mellitus: Melanocortin 4 Receptor (MC4R) and Transcription Factor 7-Like 2 (TCF7L2) genes are commonly studied candidate genes for obesity and diabetes [25,27,28,29,30,31,32,33,34,35,36,37,38,39], and the interactions of MC4R and TCF7L2 genotypes with dietary intakes on obesity [35,36] and diabetes related traits [25,30,37] have been investigated in multiple ethnic groups.