Leucine is associated with insulin resistance and a higher risk of T2DM (Adams, 2011; Lynch & Adams, 2014; Mccormack et al., 2013; Newgard et al., 2009), however, studies have also shown improved insulin sensitivity with leucine supplementation in vivo (Binder et al., 2013; Macotela et al., 2011; Nishitani et al., 2002). This evidence concerns the gene INS and type 2 diabetes mellitus.