INS and Insulin resistance: As expected, 16-week–old ob/ob mice weighed almost twice as much as their lean littermates (Fig. 1A, p < 0.001) and fasting blood glucose (p = 0.021) and insulin levels (p < 0.001) were increased in ob/ob mice, resulting in a higher homeostatic model assessment of insulin resistance (HOMA IR, p < 0.001), which indicates increased insulin resistance.