INS and Hypoglycemia: To probe changes in glucose disposal we conducted glucose-tolerance tests (GTT) and insulin-tolerance tests (ITT), finding no effect of genotype in plasma glucose levels during these challenges after normalization of baseline hypoglycemia (6-mo data shown in Fig 2G–I; GTT: N = 10/genotype/age, ANOVA, F(1,37) = 1.1, P = 0.3; Fig 2H ITT: N = 10/genotype, ANOVA, F(1,37) = 7.26, P = 0.88).