摘要:
目的 观察2型糖尿病患者无症状低血糖时心率变异性(HRV)的短程变化.方法 选择2017年1月至2018年5月在绍兴市人民医院内分泌代谢科住院或门诊选择胰岛素治疗的2型糖尿病(T2DM)患者42例,同时进行动态血糖(CGMS)和动态心电图(Holter)连续监测72h,选取低血糖(葡萄糖≤3.9 mmol/L)出现超过20 min的时段,在Holter数据中采集该低血糖时段的心率变异性(HRV)的心电数据,作短时程频域和时域分析.频域指标包括高频功率(HF,ms2)、低频功率(LF,ms2)、对HF和LF进行标准化处理(HFnu,LFnu),计算LF/HF的比值.时域指标包括正常R-R间期的标准差(SDNN),每5分钟R-R间期平均值的标准差(SDANN)、相邻RR间期之差的均方根(RMSSD)等.取同一患者非同一天低血糖相同时间段、持续同样长时间的正常血糖时段(葡萄糖5~10 mmol/L)的HRV心电数据作为自身对照,采用配对t检验.结果 42例患者中至少有一次低血糖发作的32人,共48段数据可供分析,其中夜间无症状低血糖36次.无症状低血糖时HFnu较正常血糖时明显降低[(37.68±15.57)比(45.97±13.20) ms2,t=-5.526,P<0.01],LFnu低血糖时较正常血糖时有下降趋势,但差异无统计学意义[(52.36±17.71)比(54.15±14.27) ms2,t=-0.558,P>0.05];LF/HF比值升高,差异有统计学意义(1.79±0.80比1.43±1.28,t=2.254,P<0.05).SDNN、SDANN和RMSSD在无症状低血糖时均明显下降(均P<0.05).Pearson相关性分析显示,低血糖程度与SDNN呈正相关(r=0.484,P<0.05).按低血糖程度进一步分层,共临床显著低血糖(葡萄糖<3 mmol/L)发作20次,SDANN、RMSSD较正常血糖时下降更明显,差异有统计学意义(P<0.01),HFnu下降差异仍有统计学意义(35.9±15.2比42.3±12.5,t=-2.259,P<0.05).结论 2型糖尿病无症状低血糖时心率变异性降低,减弱迷走神经反应对心脏的保护作用,通过改变交感-副交感神经平衡对心脏自主神经活动产生不利影响.%Objective To observe the change of heart rate variability(HRV)during asymptomatic hypoglycemia in patients with type 2 diabetes.Methods A total of 42 patients with type 2 diabetes who treated with insulin were enrolled.Patients were monitored with continuous glucose monitoring System (CGMS) and dynamic electrocardiogram for 72 hours.Heart rate variability was analyzed by spectral analysis during asymptomatic hypoglycemia (glucose ≤3.9mmol/L) (minimum length of 20 min).Spectral analysis including short-time frequency domain and time domain.The high-frequency,low-frequency were normalized (HFnu,LFnu),and low-frequency to high-frequency ratio were calculated.Heart rate SDNN (all NN intervals),SDANN (standard deviation of the averages of NN intervals in all 5-minute segments of entire recording),RMSSD (the square root of the mean of the sum of the squares of differences between adjacent NN intervals) were used as a time domain measure of HRV.Equal durationwith normal glucose (glucose 5-10mmol/L) at the same time period on a different day was chosen to serve as control for each hypoglycemia event.Paired t test was used for comparison.Results Among 42 patients 32 experienced at least one episode of hypoglycemia.A total of 48 data were eligible for analysis,among which 36 were asymptomatic hypoglycemia at night.Compared with euglycemia state,patients with asymptomatic hypoglycemia had significantly lower HFnu [(37.68± 15.57)vs (45.97± 13.20)ms2,P<0.01],whileLFnushoweda decreasing trend there was no significant difference [(52.36± 17.71) vs (54.15± 14.27) ms2,P>0.05].These patients also had higher low-frequency/high-frequency ratio (P<0.05).SDNN,SDANN,and RMSSD all decreased in asymptomatic hypoglycemia (all P<0.05).Pearson correlation analysis showed that the levels of hypoglycemia was positively correlated with SDNN(r=0.484,P<0.05).Further stratification was performed according to the degree of hypoglycemia.There were 20 clinically significant hypoglycemia episodes (glucose<3mmol/L),SDANN and RMSSD decreased moresignificantlycompared with euglycemia (P<0.01),and there was still decreased significant difference in HFnu (35.9± 15.2 vs 42.3± 12.5,t=-2.259,P<0.05).Conclusion Heart rate variability decreased in type 2 diabetes patients with asymptomatic hypoglycemia,indicating the loss of cardio protection of vagal nerve activity