Leptin-deficient OB/OB mice and leptin receptor-deficient db/db mice are two monogenic rodent models that have been widely studied and used as preclinical models that mimic the conditions of obesity and T2D development (Coleman, 1978; Kleinert et al., 2018; Suriano et al., 2021). This evidence concerns the gene LEPR and obesity due to melanocortin 4 receptor deficiency.