Hyperglycemia, recognized and unrecognized, as a risk factor for stroke and transient ischemic attacks.

Glycosylated hemoglobin concentration (GHb), which is considered an indication of glycemia over the preceding several months, was examined in 50 patients hospitalized for recent stroke or transient ischemic attacks (TIA), and compared to that in several reference populations. Patients with stroke or TIA had GHb (mean %A1 +/- SD, 10.2 +/- 2.3) higher than in hospital controls without cerebrovascular disease (8.3 +/- 0.9, p less than 0.005), and equivalent to values for ambulatory diabetic patients treated with diet or diet plus oral agents (9.5 +/- 2.4) or with insulin (10.7 +/- 2.9). Twenty percent (10/50) of the stroke/TIA group were previously known to have abnormal glucose tolerance or diabetes; when this subgroup was excluded, there remained 42% of the original group (21/50) with abnormal GHb (greater than 10% A1) not previously known to have hyperglycemia, and the difference between GHb values for the stroke/TIA patients not known to have glycemic abnormality and for the hospital control group remained significant (p less than 0.005). Sixty-two percent of stroke/TIA patients (31/50) were under treatment for glycemic abnormality, or had high GHb, or both. The high prevalence of elevated GHb in this population could not be attributed to a relationship to age, sex, smoking history, hypercholesterolemia, or hypertension. We conclude that hyperglycemia commonly precedes stroke and TIA, is usually unrecognized, and has been under-appreciated as a risk factor for cerebrovascular disease.