INS and type 2 diabetes mellitus: Subsequently, the elevated levels of free fatty acids can impair muscle signaling, promote hepatic gluconeogenesis, and impair glucose-stimulated insulin response, which impact the transition from normal glucose tolerance to type 2 diabetes (Ferrannini et al., 1983; Roden et al., 1996, 2000; Kashyap et al., 2003; Belfort et al., 2005; Allister et al., 2015).