Cerebral Vasomotor Reactivity in Patients with Type 2 Diabetes Mellitus Assessed by Transcranial Doppler Sonography During Hyperventilation

Abstract

Background: Cerebral autoregulation is often impaired in type 2 diabetes mellitus (T2DM), contributing to increased risk of cerebrovascular complications. Assessment of cerebral vasomotor reactivity (VMR) using transcranial Doppler sonography (TCD) during hyperventilation provides a non-invasive method to evaluate cerebrovascular function. Methods: This hospital-based cross-sectional study included 154 patients with T2DM. Cerebral blood flow velocities in the middle cerebral artery were measured using TCD at baseline and during a 90-second hyperventilation test. VMR was calculated as the percentage change in mean flow velocity. Patients were categorized based on the presence and number of diabetic microvascular complications. Statistical analysis was performed to compare groups and identify predictors of impaired VMR. Results: Of the 154 patients, 93 (60.4%) had microvascular complications. Baseline mean flow velocity and VMR were significantly lower in patients with complications compared to those without (44.37 ± 3.19 vs 52.61 ± 5.06 cm/s; 38.23% vs 49.11%, p<0.001). VMR showed a progressive decline with increasing number of complications (p<0.001). Multivariate analysis identified age, duration of diabetes, and triglyceride levels as independent predictors of impaired VMR. Conclusion: Cerebral vasomotor reactivity is significantly impaired in T2DM, particularly in patients with microvascular complications. Hyperventilation-based TCD assessment is a practical and cost-effective tool for early detection of cerebrovascular dysfunction, especially in resource-limited settings. Early identification may support improved risk stratification and prevention of neurological complications.

Keywords: Cerebral vasomotor reactivity; Transcranial Doppler; Hyperventilation test; Type 2 diabetes mellitus