Introduction: Type 1 diabetes mellitus (T1DM) is one of the most common non-communicable diseases, usually diagnosed in childhood, and has a significant impact on multiple body systems. It requires lifelong insulin therapy, and physical activity is an important treatment strategy. Cardiopulmonary exercise testing (CPET) can be used to assess the body's physiologic response to short-term minimal exercise, allowing us to determine if the response in individuals with T1DM differs from that of healthy individuals. Purpose: To determine if children with T1DM exhibit differences in metabolic, respiratory, cardiovascular, and skin microvascular response to short-term dynamic exercise to exhaustion compared to healthy peers. Methods: Eight children with T1DM and eight healthy individuals underwent CPET in which respiratory, metabolic, cardiovascular and microvascular skin parameters were measured. Most of the investigated parameters were measured noninvasively, blood glucose and lactate concentrations at rest and maximal exercise were determined from capillary blood. Results: We found no differences in heart rate response and cardiac autonomic nervous system activity between children with T1DM and healthy subjects. There were no differences in the respiratory response in both groups. In terms of metabolic parameters, oxygen consumption, carbon dioxide production and lactate concentrations before and after exercise did not differ between the two groups. However, children with T1DM had lower V̇O₂/WR and VE/V̇O₂ slopes, lower laser Doppler skin blood flow, lower skin vascular conductance and skin temperature in glabrous skin, and higher blood glucose concentrations before and after exercise. Discussion and conclusion: In children with T1DM, blood lactate concentration and cardiac autonomic nervous system activity remained unchanged compared to healthy peers, whereas children with T1DM showed poorer oxygen utilization during exercise and an altered microcirculatory response in the glabrous skin. This could be due to the higher blood glucose levels during CPET and the influence of insulin, which regulates blood flow and has a direct effect on blood glucose concentration. Maximum short-term exercise in children with T1DM is therefore safe, but adequate monitoring of blood glucose levels during and after exercise must be ensured. Further research is needed to determine the possible mechanisms of the physiological differences in T1DM compared to healthy subjects and to look for interventions that could mitigate these differences.
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