Unconscious uncoupling: dysfunctional neurovascular responses to low glucose in type 1 diabetes and impaired hypoglycemia awareness

Approximately 25% of individuals with type 1 diabetes (T1D) experience impaired awareness of hypoglycemia (IAH), a weakening of symptomatic neurohumoral responses to falling glucose levels that sharply increases risk of severe hypoglycemia. A recent study by Filip et al. used MRI-based arterial spin labeling to compare regional cerebral blood flow (CBF) responses to experimental hypoglycemia across 3 groups: individuals without T1D and individuals with T1D, with or without IAH. All groups showed a CBF response to hypoglycemia in brain regions involved in learning and interoception, among others, but the responses were qualitatively different between groups and blunted in the presence of IAH. The association between the regional CBF and the hormonal responses to hypoglycemia was inverted in IAH, compared with that in individuals with preserved awareness. The findings add to work linking changes in cognitive processing to IAH development and its persistence in some individuals.