Impaired dynamic cerebral autoregulation during isometric exercise in patients with type 2 diabetes

Abstract

Studies have shown that cerebral autoregulation (CA) is well maintained during physical activity in healthy adults. Whether type 2 diabetes (T2D) influences cerebral vascular control during exercise is currently unknown. This becomes an important question considering the associated vascular complications of diabetes. Thus, in six T2D patients (58±2 yrs) and four age matched controls (56±4 yrs) middle cerebral artery blood velocity, arterial blood pressure (BP), and end-tidal carbon dioxide (ETCO2) were measured at rest and during 2 min bouts of moderate (MEx) and high (HEx) intensity isometric handgrip performed at 20% and 40% maximum voluntary contraction, respectively. To estimate dynamic CA, the rate of regulation (RoR) was calculated from the change in cerebral vascular conductance during the rapid fall in BP following bilateral thigh cuff release performed at rest and 30s prior to the cessation of handgrip. The reduction in BP after cuff release was similar between groups and conditions (P>0.05). During MEx, the RoR was not significantly different from rest in T2D or controls. In contrast, although well maintained in controls during HEx, the RoR was reduced by 32±4% from rest in T2D patients (0.376±0.020/s rest vs. 0.256±0.019/s HEx; P<0.01). ETCO2 was unchanged throughout in both groups. These preliminary findings suggest that type 2 diabetes impairs dynamic CA during high intensity isometric exercise.