Supplement to: Hippocampal neurochemical profile and glucose transport kinetics in patients with type 1 diabetes

Context Longstanding type 1 diabetes (T1D) may lead to alterations in
hippocampal neurochemical profile. Upregulation of hippocampal glucose
transport as a result of recurrent exposure to hypoglycemia may preserve
cognitive function during future hypoglycemia in subjects with T1D and
impaired awareness of hypoglycemia (IAH). The effect of T1D on hippocampal
neurochemical profile and glucose transport is unknown. Objective To test
the hypothesis that hippocampal neurochemical composition is altered in
T1D and glucose transport is upregulated in T1D with IAH. Design and
participants Hippocampal neurochemical profile was measured with
single-voxel magnetic resonance spectroscopy at 3T during euglycemia in 18
healthy controls (HC), 10 T1D with IAH, and 12 T1D with normal awareness
to hypoglycemia (NAH). Additionally, 12 HC, 8 T1D-IAH, and 6 T1D-NAH were
scanned during hyperglycemia to assess hippocampal glucose transport with
metabolic modeling. Setting University medical center. Main Outcome
Measures Concentrations of hippocampal neurochemicals measured during
euglycemia and ratios of maximal transport rate to cerebral metabolic rate
of glucose (Tmax/CMRGlc), derived from magnetic resonance
spectroscopy–measured hippocampal glucose as a function of plasma glucose.
Results Comparison of hippocampal neurochemical profile revealed no group
differences (HC, T1D, T1D-IAH, and T1D-NAH). The ratio
Tmax/CMRGlc was not significantly different between the groups,
T1D-IAH (1.58 ± 0.09) and HC (1.65 ± 0.07, P = 0.54),
between T1D-NAH (1.50 ± 0.09) and HC (P = 0.19), and between
T1D-IAH and T1D-NAH (P = 0.53). Conclusions Subjects with T1D
with sufficient exposure to recurrent hypoglycemia to create IAH did not
have alteration of Tmax/CMRglc or neurochemical profile compared
with participants with T1D-NAH or HC.