Peripheral Chemoreflex Sensitivity is Augmented in Human Type 2 Diabetes

Abstract

IntroductionThe peripheral chemoreceptors have been implicated in the pathogenesis of type 2 diabetes. Our main objective was to examine peripheral chemosensitivity in individuals with type 2 diabetes, as well as the contribution of the peripheral chemoreceptors to basal cardiovascular control. We hypothesized individuals with type 2 diabetes exhibit exaggerated peripheral chemoreflex sensitivity to hypoxia compared to healthy, non‐diabetic controls. We further hypothesized the peripheral chemoreceptors contribute to cardiovascular dysfunction in type 2 diabetes.MethodsEight adults with diagnosed type 2 diabetes (3M/5F, 54±3 yrs, HbA1c 8.1±0.6%) and nineteen healthy controls (8M/11F, 50±3 yrs, HbA1c 5.3±0.1%) participated (IRB #2010295 and #2018486). Ventilatory and hemodynamic responses to acute hypoxia were assessed to determine peripheral chemosensitivity [i.e., hypoxic ventilatory (HVR), heart rate (HHRR) and blood pressure (HBPR) response]. Separately, heart rate, blood pressure and forearm blood flow (Doppler ultrasound) were measured while breathing normoxic or hyperoxic air (100% O2; Modified Dejours test) to acutely attenuate peripheral chemoreceptor activity. Forearm blood flow was normalized for mean arterial blood pressure for measures of vascular resistance.ResultsPeripheral chemosensitivity was augmented in adults with type 2 diabetes compared to control as assessed via the HVR (‐1.10±0.16 vs ‐0.50±0.10 L/min/%, p<0.01) and HBPR (‐0.92±0.17 vs ‐0.42±0.19 mmHg/%, p=0.06), with no differences in HHRR (‐0.68±0.22 vs ‐0.56±0.12 beats/min/%, p=0.64). Higher HVR and HBPR were associated with higher fasting insulin (R=‐0.58, p<0.01 and R=‐0.38, p=0.06) and HbA1c (R=‐0.60, p<0.01 and R=‐0.39, p=0.05). Attenuation of peripheral chemoreceptor activity with acute hyperoxia decreased heart rate (p<0.01) and blood pressure (p=0.02), with no effect on forearm vascular resistance (p=0.55); any effect of hyperoxia did not differ between adults with type 2 diabetes and controls (p>0.05).ConclusionIndividuals with type 2 diabetes exhibit exaggerated peripheral chemoreflex sensitivity which is associated with disease severity (i.e., HbA1c). In contrast, the contribution of the peripheral chemoreceptors to basal cardiovascular function in type 2 diabetes does not differ from non‐diabetic controls. Results advance our understanding of the pathogenesis of type 2 diabetes and related complications.