Muscle Oxygen Supply Impairment during Exercise in Poorly Controlled Type 1 Diabetes

oxygen (O2) uptake (V̇O2max), is impaired in poorly controlled patients with type 1 diabetes. The mechanisms underlying this impairment remain to be explored. This study sought to investigate whether type 1 diabetes and high levels of glycated hemoglobin (HbA1c) influence O2 supply including O2 delivery and release to active muscles during maximal exercise.Methods: Two groups of patients with uncomplicated type 1 diabetes (T1D-A, n = 11, with adequate glycemic control, HbA1c G7.0%; T1D-I, n = 12 with inadequate glycemic control, HbA1c 98%) were compared with healthy controls (CON-A, n = 11; CON-I, n = 12, respectively) matched for physical activity and body composition. Subjects performed exhaustive incremental exercise to determine V̇O2max. Throughout the exercise, near-infrared spectroscopy allowed investigation of changes in oxyhemoglobin, deoxyhemoglobin, and total hemoglobin in the vastus lateralis. Venous and arterialized capillary blood was sampled during exercise to assess arterial O2 transport and factors able to shift the oxyhe-moglobin dissociation curve. Results: Arterial O2 content was comparable between groups. However, changes in total hemoglobin (i.e., muscle blood volume) was significantly lower in T1D-I compared with that in CON-I. T1D-I also had impaired changes in deoxyhemoglobin levels and increase during high-intensity exercise despite normal erythrocyte 2,3-diphosphoglycerate levels. Finally