Low total haemoglobin mass, blood volume and aerobic capacity in men with type 1 diabetes

Blood O₂ carrying capacity affects aerobic capacity (VO_2max). Patients with type 1 diabetes have a risk for anaemia along with renal impairment, and they often have low VO_2max. We investigated whether total haemoglobin mass (tHb-mass) and blood volume (BV) differ in men with type 1 diabetes (T1D, n = 12) presently without complications and in healthy men (CON, n = 23) (age-, anthropometry-, physical activity-matched), to seek an explanation for low VO_2max. We determined tHb-mass, BV, haemoglobin concentration ([Hb]), and VO_2max in T1D and CON. With similar (mean ± SD) [Hb] (144 vs. 145 g l⁻¹), T1D had lower tHb-mass (10.1 ± 1.4 vs. 11.0 ± 1.1 g kg⁻¹, P < 0.05), BV (76.8 ± 9.5 vs. 83.5 ± 8.3 ml kg⁻¹, P < 0.05) and VO_2max (35.4 ± 4.8 vs. 44.9 ± 7.5 ml kg⁻¹ min⁻¹, P < 0.001) than CON. VO_2max correlated with tHb-mass and BV both in T1D (r = 0.71, P < 0.01 and 0.67, P < 0.05, respectively) and CON (r = 0.54, P < 0.01 and 0.66, P < 0.001, respectively), but not with [Hb]. Linear regression slopes were shallower in T1D than CON both between VO_2max and tHb-mass (2.4 and 3.6 ml kg⁻¹ min⁻¹ vs. g kg⁻¹, respectively) and VO_2max and BV (0.3 and 0.6 ml kg⁻¹ min⁻¹ vs. g kg⁻¹, respectively), indicating that T1D were unable to reach similar VO_2max than CON at a given tHb-mass and BV. In conclusion, low tHb-mass and BV partly explained low VO_2max in T1D and may provide early and more sensitive markers of blood O₂ carrying capacity than [Hb] alone.