Endocrine Abstracts

Standard Autonomic Function tests AFT may not detect subclinical CAN. Modalities exist (Frequency Domain) using PSA of HRV, which may detect subclinical CAN.

We performed standard AFTs (HR response to deep breathing, Valsalva, Tilt at 1 min and 6 min) and PSA of HRV on these tests in 46 subjects (29 DM and 17 Controls) matched for age and sex. We sought to establish if those DM subjects considered normal by AFT would exhibit abnormalities in PSA of HRV. We measured mean spectrum RR interval and LF/HF ratio (measures of sympathovagal tone).

Diabetic Subjects were divided into group A (normal AFT), group B (any abnormal AFT), and to subgroup B1–3 by number of abnormal AFTs.

We then sought to identify if subjects in Group A would demonstrate differences in results of PSA of HRV tests compared to controls, which might suggest subclinical CAN.

Results: In standard AFT, HRV in deep breathing was 22±10 beats/min in Group A and 20±6 beats/min in Control, P=NS. In contrast results of PSA of HRV show that LF/HF ratio in deep breathing was 7.1±3.3 (Control), 3.3±1.6 (Group A) and 1.8±1.5 (Group B), 1.2±0.6 (GroupB2), 2.3±1.6 (Group B3), P<0.01 Control vs Group A and Group B. P<0.001 Control vs Groups B1, B2, B3.

Summary: LF/HF ratio to deep breathing is a useful parameter to detect presence of subclinical CAN and to stratify severity of CAN. It may be useful as a screening test for the presence of subclinical CAN in subjects with diabetes mellitus.