In the present study we assessed the time course of adaptations in peak oxygen uptake (V̇O2peak) and muscle fractional oxygen (O2) extraction (using near-infrared spectroscopy) following 12 weeks of low-volume high-intensity interval training (HIIT) vs. moderate-intensity continuous endurance training (MICT) in adults with uncomplicated type 2 diabetes (T2D). Participants with T2D were randomly assigned to MICT (n = 12, 50 min of moderate-intensity cycling), HIIT (n = 9, 10 x 1 min at ~90% maximal heart rate) or to a non-exercising control group (n = 9). Exercising groups trained 3 times per week and measurements were taken every 3 weeks. The rate of muscle deoxygenation (i.e. deoxygenated haemoglobin and myoglobin concentration, Δ[HHb+Mb]) profiles of the vastus lateralis muscle were normalised to 100% of the response, plotted against % power output (PO) and fitted with a double linear regression model. V̇O2peak increased (P<0.05) by week 3 of MICT (+17%) and HIIT (+8%), with no further significant changes thereafter. Total increases in V̇O2peak posttraining (P<0.05) were 27% and 14% respectively. The %∆[HHb+Mb] vs %PO slope of the first linear segment (slope1) was reduced (P<0.05) beyond 3 weeks of HIIT and MICT with no further significant changes thereafter. No changes in V̇O2peak or slope1 were observed in the control group. Low-volume HIIT and MICT induced improvements in V̇O2peak following a similar time course and these improvements were likely, at least in part, due to an improved microvascular O2 delivery.