Exercise capacity is related to attenuated responses in oxygen extraction and left ventricular longitudinal strain in asymptomatic type 2 diabetes patients

Type 2 diabetes mellitus (T2DM) is associated with reduced exercise capacity and cardiovascular diseases, both increasing morbidity and risk for premature death. As exercise intolerance often relates to cardiac dysfunction, it remains to be elucidated to what extent such an interplay occurs in T2DM patients without overt cardiovascular diseases. Design: Cross-sectional study, NCT03299790.

Fifty-three T2DM patients underwent exercise echocardiography (semi-supine bicycle) with combined ergospirometry. Cardiac output (CO), left ventricular longitudinal strain (LS), oxygen uptake (O₂), and oxygen (O₂) extraction were assessed simultaneously at rest, low-intensity exercise, and high-intensity exercise. Glycaemic control and lipid profile were assessed in the fasted state. Participants were assigned according to their exercise capacity being adequate or impaired (EX_adequate: O_2peak <80% and EX_impaired: O_2peak ≥80% of predicted O_2peak) to compare O₂ extraction, CO, and LS at all stages. Thirty-eight participants (EX_impaired: n = 20 and EX_adequate: n = 18) were included in the analyses. Groups were similar regarding HbA1c, age, and sex (P > 0.05). At rest, CO was similar in the EX_impaired group vs. EX_adequate group (5.1 ± 1 L/min vs. 4.6 ± 1.4 L/min, P > 0.05) and increased equally during exercise. EX_impaired patients displayed a 30.7% smaller increase in O₂ extraction during exercise compared to the EX_adequate group (P = 0.016) which resulted in a lower O₂ extraction at high-intensity exercise (12.5 ± 2.8 mL/dL vs. 15.3 ± 3.9 mL/dL, P = 0.012). Left ventricular longitudinal strain was similar at rest but increased significantly less in the EX_impaired vs. EX_adequate patients (1.9 ± 2.5% vs. 5.9 ± 4.1%, P = 0.004).

In asymptomatic T2DM patients, an impaired exercise capacity is associated with an impaired response in oxygen extraction and myocardial deformation (LS).

Effect of High-intensity Interval Training on Cardiac Function and Regulation of Glycemic Control in Diabetic Cardiomyopathy (https://clinicaltrials.gov/ct2/show/NCT03299790).