Clinical manifestations and evaluation of cardiac autonomic neuropathy in diabetes mellitus and metabolic syndrome

A serious complication of type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) is a dysfunction of the autonomic nervous system, which requires early evaluation for the effective treatment. The possibilities of pulse oximetry, which allows to assess heart rate variability in screening of autonomic nervous system dysfunction in patients with T2DM and MetS, have not yet been studied sufficiently. Objective: to evaluate the pulse oximetry effectiveness by comparing its results with the data of quantitative autonomic testing (QAT) to detect cardiac autonomic neuropathy (CAN) and clarify its degree in patients with T2DM and MetS. Patients and methods. The study included 30 patients with T2DM (mean age 63±7.9 years), 30 patients with MetS (mean age 61.5±9.1 years), 30 subjects from the control group (mean age 49.7±9.3 years). Patients underwent pulse oximetry, basic cardiovascular reflex tests, assessment of subjective sensations according to the NSC questionnaire, the severity of neurological deficit in the legs according to the NIS-LL scale and neuropathic pain syndrome according to the NTSS-9 scale. Results and discussion. In the group of patients with T2DM, severe CAN was detected in 13.3% of patients, moderate – in 40%. In the group of patients with MetS, severe CAN was detected in 10% of patients, moderate – also in 10%. In the control group, signs of moderate CAN were detected only in 3.3% of patients. The results of pulse oximetry tests with deep breathing were comparable to the QAT results (p<0.001). Conclusion. Pulse oximetry can be used to diagnose CAN.