Traditionally, it has been accepted that hyperglycemia (high blood sugar) at the acute stage of traumatic brain injury is associated with increased mortality and poor outcome. It has also, however, been shown that insulin therapy to reduce this hyperglycemia can induce hypoglycemia (low blood sugar), which is also associated with poor outcome.
Researchers recently completed an animal study in order to get a more precise picture of how hyperglycemia affects the brain in both acute and chronic stages of traumatic brain injury. There were three major outcomes:
- Hyperglycemia at the time of trauma did not increase cortical contusion volume.
- There was no adverse effect of hyperglycemia on motor skills or memory at the acute stage of trauma. Short-term memory was actually improved.
- Sustained hyperglycemia reduced cerebral edema. Insulin treatment was detrimental to this neuroprotective effect.
In conclusion, the authors suggested that neither acute nor sustained hyperglycemia negatively affects outcome in TBI. Furthermore, insulin intervention may increase secondary brain injury (edema).
Hill J, Zhao J, & Dash PK. High blood glucose does not adversely affect outcome in moderately brain injured rodents. Journal of Neurotrauma. (June 2010).