We confirmed that obesity and hyperglycemia over 400 mg/dL develop in db/db animals as early as 7 weeks of age, while littermate misty mice with a WT Lepr gene (m/m) maintain fasting glucose levels below 200 mg/dL (Figure 5—figure supplement 1A, B). Here, LEPR is linked to obesity due to melanocortin 4 receptor deficiency.