ESPE Abstracts

Background: ‘Dead in Bed syndrome’ mechanism in childhood diabetes remains unknown. The hypothesis is that a nocturnal hypoglycaemia could lead to arrhythmias related to abnormal ventricular repolarisation.

Objective and hypotheses: To look for a relationship between spontaneous fluctuations of nocturnal glycaemia, ventricular repolarization and heart rate variability (HRV) in prepubertal children with type 1 diabetes.

Method: Continuous glycemic together with electrocardiographic monitoring were performed for 1–2 nights at home in 29 prepubertal children with type 1 diabetes. QT apex length and HRV (linear and non linear methods) were compared between hypoglycemic and normoglycaemic periods and between hyperglycemic and normoglycaemic periods. We evaluated correlations between HRV and ventricular repolarization parameters recorded in a stable euglycaemic period and clinical and biological variables (age, sex, BMI, duration of diabetes, HbA1c, percentage of hypoglycemia over the past 3 months).

Results: No difference for QT length or HRV parameters were found between periods of hypoglycemia (n=6) and hyperglycaemia (n=17) compared to euglycaemic phases. During euglycaemic phases (n=21), lower low frequency (LF) was significantly correlated with the frequency of hypoglycemia over the past 3 months (P=0.03). Tiertile comparison analysis confirmed it and found significant differences between children with high and low hypoglycaemias frequency in LF, SD2 (P<0.05). There was a negative correlation between Alpha 1 and HbA1c (P=0.03) and high frequency (HF) tended to be positively correlated with HbA1c (P=0.05). Tiertile comparison analysis found significant differences between children with high and low HbA1c in HF, rmssd, SD1 (P<0.05).

Conclusion: We did not find that spontaneous nocturnal glycemic variations, including hypoglycemia, induced changes in ventricular repolarization and heart rate variability in prepubertal children with type 1 diabetes. However, frequent hypoglycaemias over the past 3 months could have an influence on nocturnal autonomic balance.

Funding: This work was supported by the COREC Grant (CHU Rennes) (2010).