Abnormal Heart Rate Recovery after 6-minute Walk Test is Associated with Diabetic Retinopathy in Patients with Type 2 Diabetes Mellitus: A Preliminary Study

Diabetic retinopathy is associated with cardiac autonomic dysfunction in patients with diabetes mellitus. Abnormal heart rate recovery (HRR) after exercise can be used as a marker of reduced cardiac autonomic function in submaximal and symptom-limited exercise stress testing. The 6-minute walk test (6MWT) is considered as a submaximal test that is more appropriate to assess the capacity of performing activities of daily living, and can be applied to a variety of patients in clinical settings without the need of sophisticated equipment. The aim of the present study was to investigate the association of diabetic retinopathy with HRR after 6MWT in patients with Type 2 diabetes mellitus (T2DM).A total of 60 patients with T2DM completed the study. The participants were divided into four groups for further analyses according to the values of HRR. The results indicated that the group with lower HRR value had a significantly higher resting heart rate, a less increased heart rate and a relatively smaller 6MWT distance. There was also a trend towards higher possibility of developing diabetic retinopathy among the T2DM patients with a lower HRR, poor cardiac autonomic function.HRR after the 6MWT can be easily conducted and promoted for clinical applications; however, it had not been used in related study to test the cardiac autonomic nerve function for T2DM patients. More research is needed to demonstrate whether or not that the HRR after the 6MWT can be used as an indicator of cardiac autonomic function and diabetic retinopathy in T2DM, and as a performance indicator for the assessment of patient receiving rehabilitation courses.