Exaggerated exercise pressor reflex in uncomplicated type 1 diabetes and its association with oxidative stress.

Adults with type 1 diabetes (T1D) often exhibit exaggerated increases in blood pressure during exercise, but the mechanisms driving this abnormal response remain unclear. We investigated whether heightened activation of the exercise pressor reflex and oxidative stress contribute to this phenomenon. Fifteen adults with uncomplicated T1D (7 women; 27 ± 10 yr; HbA1c 7.1 ± 1.5%) and 20 healthy adults (11 women; 26 ± 9 yr; HbA1c 5.1 ± 0.3%) performed graded intensities of isometric handgrip, followed by postexercise ischemia (PEI) to isolate the muscle metaboreflex and a cold pressor test (CPT). Beat-to-beat mean arterial pressure (MAP) and heart rate were recorded continuously, and serum oxidized LDL (oxLDL), a marker of oxidative stress, was measured. Patients with T1D exhibited a greater pressor response during handgrip exercise [e.g., 40% maximal voluntary contraction (MVC) ΔMAP in T1D = 41 ± 10 vs. healthy = 34 ± 9 mmHg, P = 0.047], and this augmented pressor response was evident as early as 30 s of isometric handgrip. In contrast, MAP responses during PEI (last 30 s of PEI at 40% MVC; T1D = 34 ± 11 vs. healthy = 32 ± 11 mmHg; P = 0.774) and CPT were not different between the groups. Serum oxLDL concentration was significantly elevated in patients with T1D and positively correlated with the magnitude of exercise pressor response (e.g., 40% MVC handgrip; r = 0.744, P = 0.006). Altogether, these findings suggest that patients with T1D have augmented increases in exercise pressor reflex, likely driven by heightened muscle mechanoreflex activity. Importantly, elevated oxidative stress is a potential underlying mechanism that at least, in part, contributes to the exaggerated exercise pressor response in patients with T1D.NEW & NOTEWORTHY Patients with type 1 diabetes (T1D) exhibit exaggerated pressor response during isometric handgrip, which was apparent at 30 s following the onset of contraction. When the muscle metaboreflex was isolated, pressor response was not different across the groups, indicating that augmented pressor response may be primarily driven by mechanosensitive afferents. Elevated oxLDL in T1D was positively correlated with exercise pressor response, suggesting that oxidative stress potentially contributes to the augmented exercise pressor response in T1D.