The cardiac autonomic modulation and exercise capacity, which are strong predictors of cardiovascular and overall mortality, are reduced in type 2 diabetes (T2DM) and hypertension. New indices from non-linear modeling have been recently proposed as a method to describe the complexity of heart rate (HR) dynamics. Variables from cardiopulmonary exercise test (CPET), as circulatory power (CP), ventilatory power (VP), and oxygen uptake efficiency slope (OUES) have been used as important markers of exercise limitation. However, whether a coexistence of T2DM and systemic arterial hypertension (SAH) impairs these new markers is not yet elucidated.
PURPOSE: The purpose of the present study was to verify the impact of SAH in T2DM patients on autonomic nervous system at rest.
METHODS: We evaluated 60 participants (42 male and 18 female), diagnosed with T2DM; subjects were divided in two groups: T2DM patients (n=30; 51±7 years old) and T2DM + SAH patients (n=26; 51.42±7 years old). HR and RR interval were obtained in supine position at rest. Linear and nonlinear indices of heart rate variability (HRV) were calculated using Kubios HRV software. Pulmonary gas exchange was measured breath-by-breath, using a portable telemetric system during maximal incremental exercise testing on a cycle ergometer. Statistical analysis included Shapiro-Wilk test, followed by Pearson correlation and linear regression.
RESULTS: The OUES was influenced by SD1 (interaction effects: R2 = -0.28, p < 0.005) and VP (R2 = -0.32, p < 0.03) when both groups were considered together. When we considered the T2DM + SAH group, we also found an ApEn influence on OUES (R2 = -0.40, p < 0.05) and VP (R2 = -0.48, p < 0.02). Considering just the T2DM group we found that only ApEn predicted OUES (R2 = -0.40, p < 0.03).
CONCLUSION: These results can potentially indicate increased cardiovascular risk for adverse events, once the cardiac autonomic and exercise capacity are reduced. These data, together suggest that the coexistence of T2DM +SAH can lead to impaired cardiopulmonary and cardiocirculatory responses.