INS and hyperinsulinism: We have previously demonstrated that hypercarnitinemia combined with hyperinsulinemia (achieved via intravenous infusion of insulin [105 mU·m−2·min−1] for 6 h) also increased plasma carnitine clearance by ∼15% and resulted in an increase in skeletal muscle total carnitine content of ∼15% (Stephens et al., 2006a).