INS and Hyperinsulinemia: We have previously shown that high-fat feeding of lean mouse strains led to increased weight gain, hyperinsulinemia and glucose-mediated insulin secretion but not an expansion of islet area.21, 46 Here we have shown that an LCHFD reduced glycemic variability after a meal, but it was not able to improve β-cell function or mass in prediabetic NZO mice.