Figure 2.

Regions of enhanced 18-fluoro-deoxy-glucose uptake during hypoglycemia displayed on magnetic resonance imaging brain slices. A: Relatively greater 18-fluoro-deoxy-glucose uptake in amygdala, cerebellum, and brainstem in people with type 1 diabetes and hypoglycemia awareness than in people with type 1 diabetes and hypoglycemia unawareness, consistent with a greater anxiety and vigilance response in the former. B: Relatively reduced 18-fluoro-deoxy-glucose uptake in the right lateral orbitolfrontal cortex in people with good awareness of hypoglycemia compared with those who are unaware. The reduced activation of this brain region in those with awareness suggested by these data is compatible with the recognition of the unpleasantness or danger of the stimulus encouraging behavior to avoid hypoglycemia in future. This seems to be significantly less effective in those who are unaware. Reprinted with permission from Mason et al. (28).