The effects of relative hyperglycemia on neurovascular coupling magnitude in healthy participants: Impact of biological sex

Neurovascular coupling (NVC) is a process that ensures adequate blood flow to brain regions with higher metabolic demands, and is one of several mechanisms in place to maintain cerebral blood flow (CBF) and support neuronal homeostasis. Previous research demonstrated the robustness of NVC responses to blood gas challenges. However, other studies found attenuation in NVC responses in individuals with metabolic disorders, and there are well-documented differences in glucose metabolism between males and females. We investigated NVC responses before and after acute oral glucose ingestion, including possible sex-specific differences in healthy males and females. We recruited 36 participants (18 males:18 females) and used transcranial Doppler ultrasound to measure (a) resting cerebral blood velocity (CBV) in the posterior cerebral artery (PCAv) and (a) NVC responses using a series of five visual stimuli (VS) trials (360rpm/6Hz strobe light). Testing occurred before (fasted; FAST) and 30-min after participants ingested a standard 75g/300ml oral glucose drink (glucose loaded; GL) to elicit acute relative hyperglycemia, confirmed via capillary blood sample and glucometer (FAST:4.79±0.36mmol/L; GL:7.55±1.23mmol/L; p