Prediabetes in acute stroke: prevalence and impact on early clinical outcomes

We aimed to characterize the burden of dysglycemia in acute stroke and evaluate whether HbA₁c, even below the diabetic threshold, is associated with neurological severity and embolic risk.

We conducted a prospective study of patients with ischemic stroke or transient ischemic attack (TIA) over six months at a German stroke center. Glycemic status was defined by glycated hemoglobin (HbA₁c) and fasting glucose per American Diabetes Association (ADA) criteria. Associations with stroke subtype, age, sex, and severity were analyzed.

Abnormal glucose metabolism was present in 449 of 714 patients (62.9%), including 236 with prediabetes (33.1%) and 213 with diabetes (29.8%). Dysglycemia was most frequent in lacunar (34/40, 85.0%), atherosclerotic stroke (77/110, 70.0%), and cryptogenic strokes (68/ 98, 69.4%). Prediabetes peaked at age 75-84 (r = 0.21; 95% CI, 0.07-0.34; p = 0.0026) and was highest in men ≥ 85 years (51.7% vs. 15.4%). Height of HbA₁c significantly correlated with stroke severity (r = 0.54; 95% CI, 0.43-0.63; p < 10⁻¹⁵) and CHA₂DS₂-VASc scores (r = 0.37; 95% CI, 0.22-0.52; p = 0.003).

Prediabetes is highly prevalent across all stroke entities and independently associated with worse neurological outcomes. HbA₁c may serve as a clinical marker for risk stratification even below diabetic thresholds. Early detection and subsequent intervention may improve stroke outcomes; however, whether prediabetes constitutes a modifiable risk factor remains to be determined in future interventional studies.