It is commonly thought that to maintain physiologic homeostasis may help to minimise the brain damage due to stroke.  Thus we generally try to avoid hyperglycaemia. 

Many patients with stroke will have hyperglycaemia so it is a common problem.   Hyperglycaemia is an independent predictor of poor outcome, but the GIST trial - a randomised controlled trial of glucose/potassium/insulin infusion compared to normal saline, for tight blood glucose control - was negative.  Unfortunately the trial was underpowered so some uncertainly persists.