Abstract 84: The Effect of Hyperglycemia on Stroke Outcome Depends on Baseline Glycosylated Hemoglobin Levels

Background and hypothesis: Patients with diabetes mellitus (DM) are less likely to develop adverse outcomes than are those without DM in response to acute elevations in plasma glucose after stroke. We hypothesized that baseline glycosylated hemoglobin (HbA1c) level, which provides an estimate of long-term plasma glucose concentration, inversely correlated with clinical and tissue outcome in acute ischemic stroke patients presenting with hyperglycemia. Methods: Within the context of an ongoing prospective study (Heart-Brain Interactions Study), we measured plasma glucose and HbA1c levels in 1080 patients with acute ischemic stroke within 72 hours of symptom onset. We classified patients into 3 HbA1c strata based on the American Diabetes Association criteria: group-I (HbA1c <5.7%, n=439), group-II (HbA1c: 5.7 to 6.4%, n=290), group-III (known DM or HbA1c >6.4, n=351). We examined the relationship between admission blood glucose level, acute infarct volume on DWI, and unfavorable outcome (mRS≥3) at 3 months in each HbA1c stratum. Results: The probability of unfavorable outcome decreased by increasing baseline HbA1c level; the OR (95% CI) for unfavorable outcome for every 10 mg/dl increase in glucose level was 1.42 (1.25-1.62) in group-I, 1.19 (1.07-1.33) in group-II, and 1.02 (0.99-1.05) in group-III. When hyperglycemia was defined as ≥144 mg/dl, OR (95% CI) for unfavorable outcome was 6.53 (2.65-16.14) in group-I, 1.56 (0.77-3.15) in group-II, and 1.35 (0.78-2.33) in group-III. Adjusting for age and sex did not change the results. For every 10 ml elevation in plasma glucose, the mean infarct volume increased by 7.45 ml (5.04-9.85) in group-I, 4.96 ml (2.82-7.09) in group-II, and 0.73 ml (-0.24-1.70) in group-III. Conclusions: Chronic hyperglycemia appears to protect from deleterious effects of acute elevations in blood glucose after ischemic stroke. Further research is warranted examining whether baseline HbA1c concentration predicts benefit from interventions for glycemic control in acute stroke.