Moreover, muscle carnosine correlated positively with metabolic substrate preference for glucose as inidicated by fasting respiratory quotient RQ (Fig 1D), and negatively with delta RQ, a parameter defining the whole body metabolic flexibility (an increase in RQ in response to the experimental euglycemic hyperinsulinemia, the state of maximal insulin-induced glucose uptake) (r = -0.421, p = 0.031). The gene discussed is INS; the disease is hyperinsulinism.