1 Department of Endocrinology and Internal Medicine, Aarhus University Hospital and Medical Research Laboratory, Institute of Clinical Research, Aarhus University , Aarhus, Denmark .
2 Department of Health Science and Technology, Aalborg University , Aalborg, Denmark .
Diabetes Technol Ther. 2017 Feb;19(2):91-95. doi: 10.1089/dia.2016.0342.
We have recently shown how the combination of information from continuous glucose monitor (CGM) and heart rate variability (HRV) measurements can be used to construct an algorithm for prediction of hypoglycemia in both bedbound and active patients with type 1 diabetes (T1D). Questions remain on how cardiovascular autonomic neuropathy (CAN) influences these measurable changes. This study aims to examine if changes in HRV during hypoglycemia are confounded by the presence of CAN.
Twenty-one adults (hereof 13 men) with T1D prone to hypoglycemia were recruited and monitored with CGM and a Holter device while they performed normal daily activities. CAN was diagnosed using two cardiac reflex tests: (1) deep breathing and (2) orthostatic hypotension and end organ symptoms. Early CAN was defined as the presence of one abnormal reflex test and severe CAN was defined as two abnormal tests or one abnormal test combined with symptoms of autonomic neuropathy.
A total of 19 hypoglycemic and corresponding euglycemia periods were identified among the 21 patients. Eleven patients were diagnosed with CAN, hereof five with severe CAN. The HRV parameter low frequency (LF) was significantly (P = 0.029) reduced during hypoglycemia. Changes in LF during hypoglycemia were not different between patients with and without CAN, -0.64 versus -0.48 log(LF) (P = 0.74).
Our data show that there are measurable changes in HRV during hypoglycemia, and present in both patients with and without CAN.
我们最近展示了如何结合连续血糖监测（CGM）和心率变异性（HRV）测量的信息，构建 1 型糖尿病（T1D）卧床和活跃患者低血糖预测算法。关于心血管自主神经病变（CAN）如何影响这些可测量变化仍存在疑问。本研究旨在检查低血糖期间 HRV 的变化是否受到 CAN 的影响。
招募了 21 名易发生低血糖的 T1D 成年人（其中 13 名男性），并用 CGM 和动态心电图仪监测他们在进行日常活动时的情况。使用两种心脏反射测试来诊断 CAN：（1）深呼吸和（2）直立性低血压和终末器官症状。早期 CAN 定义为存在一项异常反射测试，严重 CAN 定义为两项异常测试或一项异常测试合并自主神经病变症状。
在 21 名患者中，共确定了 19 次低血糖和相应的血糖正常期。11 名患者被诊断为 CAN，其中 5 名患有严重 CAN。HRV 参数低频（LF）在低血糖期间显著降低（P=0.029）。低血糖期间 LF 的变化在有无 CAN 的患者之间没有差异，分别为-0.64 与-0.48 log（LF）（P=0.74）。
我们的数据表明，在低血糖期间存在 HRV 的可测量变化，并且在有无 CAN 的患者中均存在。
