Correlation between Cardiac Autonomic Function Test and Subclinical Neuropathy in Type 1 Diabetic Children

Jeong, Hye Cheon; Han, Heon Seok; Lee, Sang Su; Kim, Young Gye

Abstract

PURPOSE
Autonomic neuropathy in adult diabetics is known to be common and poor in prognosis. Cardiac autonomic neuropathy increases sudden cardiac death and is present before apparant cardiac symptoms. Subclinical diabetic peripheral neuropathy is common with type 1 diabetes. In children, few studies for subclinical peripheral neuropathy and cardiac autonomic neuropathy were reported but the results were inconsistent. The authors investigated subclinical cardiac and peripheral neuropaties and evaluated correlation between nerve conduction velocity(NCV) and cardiac autonomic function(CAF) test in type 1 diabetic children and adolescents
METHODS
Over 5 years from 1997 to 2002, 27 IDDM without clinical neuropathy were registered. Total 57 CAF and NCV were tested every 2 or 3 years. Duration of diabetes, average HbA1c during 1 year prior to the test, and urinary microalbumin excretion for 24 hours were assessed. Diabetic autonomic nervous function was evaluated by cardiovascular reflex test:falling systolic blood pressure in response to standing, heart rate changes in response to standing, beat-to-beat rate variation during deep breathing, RR interval change during and after Valsalva maneuver. Subclinical peripheral neuropathy was evaluated by NCV in both upper and lower extremities. Correlation of parameters according to NCV abnormality and microalbuminuria were analyzed.
RESULTS
The age, duration of diabetes and microalbuminuria were not statistically different between children with normal and abnormal NCV. The level of HbA1c was associated with NCV abnormality. In a multivariate logistic model for NCV abnormality, level of HbA1c showed statistical significance after controlling the effects of age, duration of diabetes, and urinary microalbumin level, and the odd ratio was 1.532. The degree of CAF abnormality was marginally significant in the logistic model. Children with microalbuminuria showed older age and longer duration of diabetes than those without microalbuminuria. However, mean HbA1c level was not significantly different between the two groups. Degree of CAF abnormality was not significantly associated with microalbuminuria, either. In a general linear model including urinary albumin level as the dependent variable, none of independent variables was statistically significant.
CONCLUSION
Therapy against neuropathy should be considered in patients with high HbA1c and abnormal CAF test even without clinically apparent neuropathy.