Diabetes hyperglycemia and recovery from stroke

Strokeis a major cause of death and severe disability in older people. Despite the burden of disease, there is still no safe, simple and proven medical therapy for the treatment of acute stroke. Advances in acute stroke treatment have been either consistently disappointing (neuroprotective therapy) or fraught with controversy regarding risk/benefit (thrombolysis), and attention is once again being directed towards physiological variables that may influence outcome. Both insulin‐dependent and non‐insulin‐dependent diabetes mellitus are major risk factors for stroke. Diabetes mellitus has also been shown to be associated with increased mortality and reduced functional outcome after stroke. Hyperglycemia is a frequent finding following stroke and may reflect the metabolic stress of the acute event, so‐called stress hyperglycemia, and/or underlying impaired glucose metabolism. Several large clinical studies have now demonstrated a positive association between a raised blood glucose and poor outcome from stroke; greater mortality and reduced functional recovery. What is not clear is to what extent hyperglycemia is a ‘normal’ physiological response to stroke or whether hyperglycemia per se increases cerebral damage in the acute phase. There are many potential mechanisms by which hyperglycemia can exert a harmful effect upon cerebral tissue and it is probable that an important relationship exists, not only between glucose and stroke outcome, but also between insulin and neuroprotection. It remains to be determined whether lowering and maintaining ‘normal’ glucose levels in the immediate aftermath of stroke, combined with the administration of insulin as an acute treatment, can modify this outcome.