Effect of Glycated Haemoglobin (HBA1c) on Cardiorespiratory Fitness (CRF) in a Population with Type 2 Diabetes Mellitus (T2DM): A Cross-Sectional Study

<i>Background and Objective:</i> The aim of this study was to evaluate cardiorespiratory fitness (CRF) measures, maximal oxygen consumption (VO₂ max), and minute ventilation/carbon dioxide production (V_E/VCO₂ slope and others) among the T2DM population based on glycated haemoglobin (HBA1c). <i>Material and Methods:</i> The present study comprised a cross-sectional design, with two groups, based on HbA1c values (≤7 and ≥7.1). Laboratory samples were taken to evaluate glycated haemoglobin and fasting blood glucose (FBS). Cardiopulmonary exercise testing was performed to calculate various fitness-related parameters. Data analysis: An independent <i>t</i>-test was used to analyse the outcomes in the two groups. <i>p</i> < 0.05 was considered significant. Linear regression was used to examine the influence of predictor variables on dependent variables. <i>Results:</i> A total of 70 patients agreed to participate in the study, with 19 females and 51 males. The mean (standard deviation) BMI (body mass index) of all participants was 29.7(5.2), the mean (SD) weight was 84.4 (18.9) kg, and the mean height was 167.4 (23) cm. The average age of the individuals was 52 ± 8 years. The independent <i>t</i>-test revealed a significant difference between the two groups in terms of CRF measures. <i>Conclusions:</i> The current research identified the presence of poor glycaemic control and cardiorespiratory fitness measures among the Brazilian population with T2DM. HBA1c, duration of diabetes, age, and BMI can be employed to predict the ventilatory threshold (VT) and VO₂ max.