Brain Glucose Concentrations in Patients with Type 1 Diabetes

Although it is well established that recurrent hypoglyce-mia leads to hypoglycemia unawareness, the mecha-nisms responsible for this are unknown. One hypothesis is that recurrent hypoglycemia alters brain glucose trans-port or metabolism. We measured steady-state brain glucose concentrations during a glucose clamp to deter-mine whether subjects with type 1 diabetes and hypo-glycemia unawareness may have altered cerebral glu-cose transport or metabolism after exposure to recurrent hypoglycemia. We compared 14 subjects with diabetes and hypoglycemia unawareness to 27 healthy control subjects. Brain glucose concentrations were measured under similar metabolic conditions using in vivo 1H nu-clear magnetic resonance (NMR) spectroscopy at 4 Tesla during a hyperglycemic clamp (plasma glucos