Adults with type 2 diabetes mellitus (T2D) consistently show reduced peak pulmonary oxygen uptake (VO2) responses during maximal incremental exercise (Green et al, 2015). These lower peak VO2 responses are associated with reduced peak cardiac output and greater fractional oxygen extraction levels, suggesting a reduced ability to deliver oxygen to exercising tissues. In addition, young and middle-aged adults with T2D of short duration (mean time since diagnosis = ~3-5 years) manifest slower rates of oxygen uptake (VO2 kinetics) at the onset of moderate submaximal exercise, but this effect is absent in older (> 60 years) individuals. This is likely due to a larger diabetes-induced exertional hypertension response during submaximal exercise in middle-aged compared with older people, which accompanied with normal cardiac output responses, results in blunted systemic vascular conductance responses among the former (O’Connor et al, 2015). Furthermore, peak blood flow during graded exercise is reduced and the dynamic response of blood flow during submaximal exercise is slowed in isolated lower limbs in younger and middle-aged adults with T2D (Kiely et al, 2014). These vascular defects most likely contribute to the exertional hypertension, impaired peak and dynamic responses of VO2 and exercise intolerance. As a consequence of this exercise intolerance, adults with T2D perceive even light to moderate exercise as more difficult than healthy peers, and this might contribute to their relatively lower levels of physical activity and increased risk of cardiovascular outcomes and all-cause mortality in later life.