The effect of glucose potassium insulin (GKI) infusion (compared to saline as control) within 24 hours of ischemic stroke was studied in patients (> 18 years old) with blood glucose >126mg/dl (7mmol/l) admitted to Southern General Hospital, Glasgow, Scotland. Infarct growth on MRI between baseline and day 7 was the primary endpoint. Brain lactate concentrations were measured with MR spectroscopy. Forty patients were randomized, 15 to saline and 25 to GKI infusions. From 6 to 12 hours after infusion, capillary blood glucose was lowered significantly compared to the saline group, without alteration of infarct growth. In a secondary analysis, GKI was associated with significantly greater infarct growth in patients with complete intracranial vessel occlusion compared with controls (p=0.011) Brain lactate levels were significantly lower in GKI infused patients, and increased in control subjects. Asymptomatic hypoglycemia occurred in 76% of GKI-treated patients. [1]

COMMENT. Hyperglycemia in more than 50% of acute stroke patients is an independent risk factor for poor outcome. Guidelines recommend blood glucose monitoring but optimal method of management is not established. In the above trial of insulin infusion within 24 hours of stroke, blood glucose was lowered and an increase in brain lactate was attenuated, but cerebral infarct growth was not affected. In patients with persistent arterial occlusion, GKI infusion was associated with greater infarct growth. The authors conclude that GKI infusion to treat moderate hyperglycemia in acute ischemic stroke requires further study and is not recommended in routine clinical practice.

An editorial [2] questions if the answer is in the imaging, and if intervention should be as early as possible after stroke onset. Studying the natural history of blood glucose after ischemic stroke, Wong AA et al [3] found that mean glucose levels remain static in patients with ischemic stroke without diabetes until at least 48 hours post-stroke. Levels are higher in patients with more severe stroke. Higher or lower levels regress to the mean over time.