Cardiac Autonomic Neuropathy in Diabetic Patients

The autonomic neuropathy in diabetics occurs more than 30% of cases and it is estimated that the associated cardiovascular mortality is 50%; therefore, early detection during the subclinical stage of autonomic dysfunction is useful to stratify cardiovascular risk. Objectives: To analyze the variability of heart rate (HRV) and systolic blood pressure (SBP) in short and long-standing diabetic subjects compared to control subjects in the time and frequency domain. Subjects and methods: 30 healthy subjects, 30 short-standing diabetics (SSDM), and 15 long-standing diabetic subjects (LSDM), between 30-60 years old, indistinct sex were recruited; each subject underwent a study to evaluate HRV and SBPV in clinostatism, orthostatism and rhythmic breathing (6 rpm, 0.1 Hz). Analysis was performed at time-and spectral-domain of the records. Results: Before the maneuvers, the control group had increased HR and variability, increased sympathovagal index and low frequencies. The SSDM showed a similar response to control group, but with a decrease in the variability, decrease of the low and high frequencies; and increase of SBPV in orthostatism and rhythmic breathing. The LSDM had a higher HR, without an increase in SBP; decrease in HRV and SBPV. Discussion: Although the SSDM showed a similar response in the maneuvers, there was a decrease in HRV, an increase in HR in all maneuvers and an increase in SBP indicating parasympathetic injury. And the decrease in HRV but not in the SBPV quantified in the LSDM indicates sympathetic and parasympathetic injury. Conclusions: HRV is decreased and SBPV is increased in SSDM subjects with respect to control group; and the HRV is diminished in the LSDM with respect to the other two groups.