FABP4 and type 2 diabetes mellitus: Many previous studies have shown that FABP4 is relevant to the development of metabolic diseases (e.g., atherosclerosis, insulin resistance, T2D), cardiovascular disease, asthma, and cancer (Engl et al., 2008; Prentice et al., 2019; Li et al., 2020; Lee et al., 2021a).