Cardiac autonomic dysfunction in diabetic children

OBJECTIVE - Adults with type 1 diabetes may have abnormal alterations in he art rate variability (HRV) due to cardiac autonomic neuropathy. This prospe ctive study was performed to determine whether HRV can be used to detect su bclinical autonomic neuropathy in diabetic children. RESEARCH DESIGN AND METHODS - We examined five time domain and three freque ncy domain HRV indices determined from 24-h Holter recordings in 73 diabeti c children and adolescents aged 3-18 years (mean 12.1 years) with a mean du ration of diabetes of 55 months. The measures were compared with normal ran ges. Z scores were established for each parameter and were compared with cl assic risk factors of other diabetic complications. RESULTS - Most HRV indices were significantly depressed in children aged gr eater than or equal to 11 years, and the levels of HRV abnormalities were s ignificantly correlated with long-term metabolic control (mean GHb for 4 ye ars) in that age-group. In younger patients, HRV indices were within the no rmal range and were not correlated with the level of metabolic control. Ill ness duration and microalbuminuria but not short-term metabolic control (mo st recent GHb) were also independently predictive of HRV abnormalities. CONCLUSIONS - These results suggest that early puberty is a critical period for the development of diabetic cardiac autonomic dysfunction. Therefore, all type 1 diabetic patients should be screened for this complication by HR V analysis beginning at the first stage of puberty regardless of illness du ration, microalbuminuria, and level of metabolic control.