ABSTRACT
Objective:
It’s known that prolonged high blood glucose levels during the course of diabetes mellitus (DM) lead to the development of autonomic neuropathy. In this study, we investigated the relationship between heart rate variability (HRV) and blood glycemic levels in patients clinically diagnosed with diabetes, in patients without any glucometabolic disorder, and in prediabetic patients.
Material and Methods:
In this study, 100 patients followed in Cardiology and General Internal Medicine outpatient clinics were evaluated retrospectively. Our study includes 3 different groups: 34 patients without any glucometabolic disorders, 35 patients followed up for prediabetes, and 31 patients diagnosed with diabetes. For the analysis of HRV parameters, standard deviation of normal RR intervals in 24 h (SDNN), SDNN index, root mean square of successive RR interval differences (rMSSD) and percetange of adjacent NN intervals differing by more than 50 milliseconds (pNN50), high frequency (HF), low frequency (LF) and LF/HF parameters were used.
Results:
As a result of post-hoc analyses for HRV parameters, SDNN, SDNN-index and rMSSD values were significantly lower in the diabetes group compared to the control group; very low frequency (VLF) value was found to be lower in the diabetes group compared to the other two groups. No-statistical difference was found between the groups for pNN50, HF, LF and LF/HF, but in the diabetes and pre-diabetes groups, pNN50, HF and LF were numerically lower than in the control group. Looking at the correlation between HRV parameters and FBS by group, a weak negative correlation was found between all variables except LF/HF. A weak to moderate negative correlation with HbA1c was found for SDNN, SDNN-index, rMSSD and VLF. When comparing HRV parameters by treatment type in diabetic patients, no statistically significant difference was found between patients using oral antidiabetic and those using insulin. When HRV parameters were compared by treatment status in the prediabetes group, there was no statistically significant difference between those receiving treatment and those not receiving treatment.
Conclusions:
We think that HRV parameters may be guiding in the diagnosis of cardiac-autonomic-neuropathy in patients with DM and blood glucose levels that have not yet reached pathological levels.