PRKAA1 and type 2 diabetes mellitus: In muscle samples from obese and type 2 diabetes patients, AMPK expression and activation are not significantly different from controls (Hojlund et al., 2004; Steinberg et al., 2004), suggesting that changes in AMPK signaling may not be the primary defect preceding metabolic changes associated with these conditions (Steinberg and Kemp, 2009).