GCG and type 2 diabetes mellitus: A common variant (E23K; rs5219) in KCNJ11 is associated with enhanced T2D risk (Gloyn et al. 2003) due to increased KATP-channel activity (Schwanstecher et al. 2002) and impaired glucose-induced suppression of glucagon secretion in vivo (Tschritter et al. 2002).