Consistent with studies in prediabetic mouse models of type 2 diabetes (Carvalho, Oliviera et al., 2012; Gonzalez, Merino et al., 2013; Irles, Neco et al., 2015; Amaral, Kravets et al., 2020), we found that Cx36 gap junction coupling is decreased in islets from prediabetic NOD mice as early as 9 weeks of age compared to immunodeficient controls. Here, GJD2 is linked to type 2 diabetes mellitus.