Henk M. De Feyter1, Graeme F. Mason2, Gerald I. Shulman3, Douglas L. Rothman1, Kitt Falk Petersen4
1Diagnostic Radiology, Yale University, New Haven, CT, United States; 2Dept. of Psychiatry, Yale University, New Haven, CT, United States; 3Howard Hughes Medical Institute, Yale University, New Haven, CT, United States; 4Internal Medicine, Yale University, New Haven, CT, United States
Previous 13C MRS studies have lead to the hypothesis that upregulation of blood-brain barrier monocarboxylic acid (MCA) transport may contribute to maintenance of brain energetics during hypoglycemia in subjects with hypoglycemia unawareness. We examined transport and metabolism of [3-13C]-lactate in brain of type 1 diabetic patients with hypoglycemia unawareness and non-diabetic control subjects during a hypoglycemic clamp using 13C MRS. We found that brain lactate concentrations were markedly increased in type 1 diabetic subjects. Surprisingly we observed no increased oxidation of blood-borne lactate in the type 1 diabetic subjects suggesting that other metabolic adaptations may contribute to hypoglycemia unawareness.