ADRA2A and type 2 diabetes mellitus: Notably, single-nucleotide polymorphisms in and near the ADRA2A gene (encoding α2A-adrenergic receptor) have been correlated with increased fasting glycemia and type 2 diabetes risk (Liggett, 2009; Dupuis et al., 2010; Talmud et al., 2011; Langberg et al., 2013); impaired glucose-stimulated insulin secretion is a factor in this increased risk.