INS and hyperinsulinism: Hyperinsulinemia initially present in obese rats at 2 months (10.5 ± 0.7 μg/L plasma insulin vs 0.2 ± 0.04 μg/L in lean) decreased due to ß-cell insufficiency at 3 months (3.9 ± 0.6 vs. 0.5 ± 0.09 μg/ml in lean).