FABP4 and diabetes mellitus: Fatty acid-binding protein 4 (FABP4), also named as adipocyte P2 (aP2) or adipocyte-FABP (A-FABP), is a novel adipokine involved in energy balance, ER stress and inflammation in diabetes, atherosclerosis, and kidney diseases (Furuhashi and Hotamisligil, 2008; Hotamisligil and Bernlohr, 2015).