Objective: Patients with diabetes mellitus (DM) are at an increased risk of sudden cardiac death (SCD) partly explained by cardiac autonomic neuropathy (CAN). There have been fewer studies to evaluate CAN using heart rate variability (HRV) and heart rate recovery (HRR) in patients with type 2 DM.To our knowledge, there has been no study to investigate the association between HRR, HRV and type 1 DM. The purpose of this study was to examine the changes in HRR and HRV measurements in type 1 diabetic patients.
Methods: The study population consisted of 35 consecutive patients with type 1 diabetes and 35 sex- and age-matched non-diabetic controls. We performed electrocardiography, echocardiography, Holter analysis, exercise stress test, routine biochemical tests including haemoglobin Ale, high-sensitivity C-reactive protein and evaluated the clinical characteristics. HRR was calculated by subtracting the heart rate values at the first minute of the recovery phase from the peak heart rate. Abnormal HRR was defined as HRR < or = 18 beats.The HRV analysis was performed in both time domain and frequency domain.
Results: In HRV analysis, type 1 diabetic patients had significantly lower time domain [SDNN (P=0.041), SDANN (P=0.016), r-MSSD (P<0.001), pNN50 (P<0.001)] and frequency domain [total power (P=0.002), VLF (P<0.001), LF (P<0.001), HF (P=0.001), LF/HF (P=0.034)] HRV parameters as compared to controls. In logistic regression analysis, the HRR (OR 0.927, 95% CI 0.872 to 0.985, P= 0.014), METs (OR 0.562, 95% CI 0.355 to 0.890, P= 0.014), pNN50 (OR 0.729, 95% CI 0.566 to 0.941, P= 0.015) and HF (OR 0.952, 95% CI 0.911 to 0.994, P= 0.027) were independently associated with type 1 DM.
Conclusion: The results of this study showed that HRV parameters and HRR were significantly reduced in patients with type 1 versus healthy controls. We found that HRV parameters correlated with HRR in type 1 diabetic patients. There is a relationship between CAN and inflammation and also, there may be a relationship between CAN and intensive glycaemic control according to this study.