BACKGROUND: Cardiovascular autonomic neuropathy (CAN) is a common form of autonomic dysfunction in diabetes mellitus (DM) patients, but it can be asymptomatic for years. Low baseline plasma noradrenaline levels have been found in diabetic patients, but this decrease seems to associate clinically severe autonomic neuropathy. PURPOSE: To evaluate the impact of DM on heart rate variability (HRV) parameters and to determine the correlations with plasma adrenaline and noradrenaline, as a possible mechanism of early disruption in HRV. METHODS: A group of 34 patients with type 2 diabetes mellitus, without clinical signs of CAN, was enrolled. HRV (as a measure of autonomic balance) was measured using a 24 hour ECG monitoring system in all subjects during normal daily activity. Plasma catecholamines and other laboratory markers were measured. RESULTS: HRV parameters are lower in DM group as compared with control group. More than half of the patients had HRV parameters below the normal range (54%). There are lower levels of noradrenaline value in DM, as compared with controls, but the difference is not statistically significant (p = 0.08). Adrenaline levels were similar in both groups. DISCUSSION AND CONCLUSION: CAN is best evaluated using heart rate variability (HRV) on 24 hours recordings. There is a tendency for HRV parameters to decrease even in asymptomatic patients, especially after years of evolution. We did not find significant correlations between HRV and plasma catecholamine, even if noradrenaline was lower in DM patients. Holter monitoring remains a reliable method for early diagnosis of CAN.
BACKGROUND:Cardiovascular autonomic neuropathy (CAN) is a common form of autonomic dysfunction in diabetes mellitus (DM) patients, but it can be asymptomatic for years. Low baseline plasma noradrenaline levels have been found in diabeticpatients, but this decrease seems to associate clinically severe autonomic neuropathy. PURPOSE: To evaluate the impact of DM on heart rate variability (HRV) parameters and to determine the correlations with plasma adrenaline and noradrenaline, as a possible mechanism of early disruption in HRV. METHODS: A group of 34 patients with type 2 diabetes mellitus, without clinical signs of CAN, was enrolled. HRV (as a measure of autonomic balance) was measured using a 24 hour ECG monitoring system in all subjects during normal daily activity. Plasma catecholamines and other laboratory markers were measured. RESULTS: HRV parameters are lower in DM group as compared with control group. More than half of the patients had HRV parameters below the normal range (54%). There are lower levels of noradrenaline value in DM, as compared with controls, but the difference is not statistically significant (p = 0.08). Adrenaline levels were similar in both groups. DISCUSSION AND CONCLUSION: CAN is best evaluated using heart rate variability (HRV) on 24 hours recordings. There is a tendency for HRV parameters to decrease even in asymptomatic patients, especially after years of evolution. We did not find significant correlations between HRV and plasma catecholamine, even if noradrenaline was lower in DMpatients. Holter monitoring remains a reliable method for early diagnosis of CAN.