Inter‐individual differences in rapid vasodilation in older males with and without type 2 diabetes

PURPOSE To identify if rapid vasodilatory responses differ between individuals with or without type 2 diabetes. METHODS 13 males (7 type II diabetics (T2D), 6 healthy controls (CON)) lay supine with the arm at heart level and completed 6 trials of single handgripping contractions (3 trials/day/contraction intensity, on 2 separate days, 1 s contraction duration) at 10, 20, and 40 % of their maximal voluntary contraction (randomly ordered). Forearm brachial artery blood flow (FBF, echo and Doppler ultrasound), mean arterial pressure (MAP, finger photoplethysmography) were measured continuously. RESULTS tension‐time integral of single contraction force production (kg·s) vs. FBF relationships were constructed for each individual. There was no difference in the slope (4.7 ± 2.9 vs. 4.8 ± 2.5) or y‐intercept (y‐int) (35.2 ± 32.5 vs. 23.3 ± 15.2) between T2D and CON. However, there was considerable variation in both the slope and y‐int between subjects in each group. T2D coefficient of variation (COV) of slope was 64% and y‐int was 93%. COV for the slope in CON was 52% and y‐int 65%. Despite the variation, the r 2 value for each individual was strong, ranging from 0.34–0.7 (σ = 0.51 ± 0.14) in T2D and 0.44–0.97 (σ = 0.76 ± 0.22) in CON. CONCLUSION Older males exhibit substantial inter‐individual rapid vasodilatory responses to muscle contraction. These individual differences do not appear to be influenced by type 2 diabetes.