Influence of prestroke glycemic status on outcomes by age in patients with acute ischemic stroke and diabetes mellitus

Background: This study aimed to explore the association between admission HbA1c and the risk of 1-year vascular outcomes stratified by age group in patients with acute ischemic stroke (AIS) and diabetes mellitus (DM). Methods: This study analyzed prospective multicenter data from patients with AIS and DM. Admission HbA1C were categorized as:≤6.0%, 6.1%–7.0%, 7.1%–8.0%, and >8.0%. Age was analyzed in categories:≤55 years, 56–65 years, 66–75 years, 76–85 years, and >85 years. The primary outcome was 1-year composite of stroke, MI, and all-cause mortality. The modifying effect of age on the relationships between HbA1c and 1-year primary outcome was explored by Cox proportional hazards model. Results: A total of 16,077 patients (age 69.0 ± 12.4 years; 59.4% males) were analyzed in this study. Among patients ≤55 years, the hazard ratio (HR) of the 1-year primary outcomes increased with an HbA1C > 8.0% (adjusted HR 1.39[1.13–1.70]). For patients aged 56–65 and 66–75, the highest HRs were observed for an HbA1c of 7.1–8.0% (aHRs; 1.21 [1.01–1.46] and 1.22 [1.05–1.41], respectively). In the 85+ age group, the highest HR occurred for HbA1c ≤ 6.0% (aHR 1.47 [0.98–2.19]). The HbA1c 8.0% showed evident age-dependent heterogeneity in the post hoc HR plots. Conclusion: Our study revealed that in patients with AIS and diabetes under 55, higher admission hbA1c was associated with an increased risk of the 1-year primary outcome, while in patients aged over 85, lower HbA1c value (≤6.0%) may be associated with an increased risk of vascular events. The results of our study suggest the age-stratified, heterogeneous associations between admission HbA1c and 1-year vascular outcomes in patients with AIS and diabetes.