Figure 6.

Changes in (a) brain glutamate, (b) calculated brain lactate-to-glutamate ratio, and arterial blood glucose determined by cerebral microdialysis investigating the influence of time points with insulin (grey box plots) and without insulin (white box plots) administration in pre-defined brain glucose clusters. At brain glucose levels ≤ 5 mM brain glutamate was significantly increased under the influence of insulin compared with time points without insulin administration (*P < 0.001, Mann-Whitney test). In parallel lactate-to-glutamate was significantly decreased (*P < 0.001, Mann-Whitney test). At brain glucose levels >5 mM insulin did not influence brain glutamate or lactate-to-glutamate ratio. Whenever insulin was administered, arterial blood glucose was significantly increased compared with time points insulin was not given (*P < 0.001, Mann-Whitney test).