RAPGEF1 and type 2 diabetes mellitus: There is also a T2D association with variants of human RAPGEF1 by GWAS in Chinese, Finish and Korean populations (Gaulton et al., 2008; Hong et al., 2009; Qu et al., 2011), suggesting that precocious manifestation of diabetes in NOD/NckH mice with putative null Rapgef1 mutation may result from peripheral insulin resistance combined with failing insulin production.