These models include leptin deficient ob/ob mouse, leptin receptor deficient db/db mouse, Zucker fatty rat, Zucker diabetic fatty (ZDF) rat, spontaneously hypertensive/NIH corpulent (SHR/N-cp) rat, and JCR:LA-cp rat (note that this is not a comprehensive list of all leptin or leptin receptor deficient animals since not all such models are widely used for T2DM research). The gene discussed is LEP; the disease is type 2 diabetes mellitus.