FOXO1 and type 2 diabetes mellitus: Several studies suggest that genetic variation in the FoxO1 gene is a predisposing factor for type 2 diabetes (T2D) or DKD in humans, revealing that FoxO1 may be involved in the initiation and development of DKD in patients with T2D, which provides new insight into the etiology of DKD (Müssig et al., 2009; Gong et al., 2017; Zhao et al., 2017).