C肽及胰岛自身抗体在糖尿病分型诊断中的价值研究

The Value of Serum C-Peptide and Islet Autoantibodies in the Differential Diagnosis of Diabetes Mellitus

目的探讨空腹C肽(FC-P)、餐后2小时C肽(P2hC-P)及胰岛自身抗体在糖尿病分型诊断中的价值。方法分析148例1型糖尿病(T1DM)患者与353例2型糖尿病(T2DM)患者的基本特征、实验室检查结果(包括C肽水平、胰岛自身抗体)存在的差异。根据病程将各型患者又分别分为3个亚组(0~年组、2~年组、5~年组),比较各亚组患者入院时及胰岛素强化治疗后的FC-P、P2hC-P水平差异。绘制ROC曲线分析FC-P、P2hC-P对糖尿病分型的诊断价值。结果T2DM患者年龄、病程、BMI、FC-P、P2hC-P均高于T1DM患者(均P<0.01),两组空腹血糖(FBG)、糖化血红蛋白(HbA1c)水平的差异无统计学意义(均P>0.05)。T2DM组患者谷氨酸脱羧酶抗体(GADA)、胰岛细胞抗体(ICA)、蛋白酪氨酸磷酸酶抗体(IA-2A)、锌转运蛋白8抗体(ZnT8A)均为阴性,T1DM患者GADA、ICA、胰岛素自身抗体(IAA)、IA-2A、ZnT8A的水平均显著高于T2DM患者(均P<0.01)。T2DM不同病程亚组患者的FC-P、P2hC-P水平均高于T1DM组(均P<0.05)。ROC曲线分析显示病程<2年的患者入院时检测FC-P、P2hC-P明确糖尿病分型的最佳临界值分别为0.165nmol/L、0.323nmol/L;胰岛素强化治疗后检测FC-P、P2hC-P的最佳临界值分别为0.318nmol/L、1.268nmol/L。胰岛素强化治疗后P2hC-P的AUC最大,为0.938,灵敏度为92.91%,特异度为88%,诊断准确度较高。结论C肽可作为鉴别T1DM、T2DM的指标,且餐后C肽的诊断价值高于FC-P,同时联合GADA、ZnT8A、IA-2A及年龄、BMI等临床特征可降低T1DM的临床漏诊率及误诊率。

Objective To explore the value of serum C-peptide(C-P)and islet autoantibodies in the differential diagnosis of type 1 diabetes mellitus(T1DM)and type 2 diabetes mellitus(T2DM).Methods A total of 501 patients with diabetes mellitus(DM)from April 2018 to June 2021 were included.Among them,148 patients with T1DM and 353 patients with T2DM were se-lected.The clinical data were retrospectively collected and analyzed.The patients were divided into three subg roups(0~year group,2~year group,5~year group)according to the course of DM.The levels of glutamic acid decarboxylase antibody(GA-DA),islet cell antibody(ICA),insulin autoantibody(IAA),protein tyros ine phos phatase antibody(IA-2A),zinc transporter 8 au-toantibody(ZnT8A)were compared between the two groups.The levels of fasting C-peptide(FC-P),postprandial 2 h C-peptide(P2hC-P)were compared according the course of DM.The receiver working characteristic(ROC)curve was used to analyze the best cut-off point of C-P,as well as its sensitivity and specificity of serum C-P in the patients with the disease course<2 years.Results The disease course,age,body mass index(BMI),as well as the levels of FC-P and P2hC-P were higher in the T2DM group than in the T1DM group(all P<0.01),and there were no significant differences in blood glucose and glycated he-moglobin A1c(HbA1c)between the two groups(P>0.05).The rates of GADA,ICA,IA-2A and ZnT8A in T2DM were all neg-ative,and the levels of GADA,ICA,IAA,IA-2A and ZnT8A were significantly higher in the T1DM group than in the T2DM group(P<0.01).For the patients with the disease course<K2 years,ROC curves showed that the best cut-off point of FC-P and P2hC-P measured at admission for differentiating T1DM and T2DM were 0.165,0.323 nmol/L,and the optimal cut-off point measured after intensive insulin therapy were 0.318 and 1.268 nmol/L.The area under the curve(AUC)of P2hC-P tested after intensive insulin therapy was the largest(0.937),and its sensitivity and specificity were 92.91%and 88%,respectively,indica-ting its highly diagnostic accuracy.Conclusion C-P can be used as an indicator for the differential diagnosis of T1DM and T2DM,and the diagnostic value of postprandial C-peptide(PC-P)is greater than FC-P.At the same time,C-P combined with GADA,ZnT8A,IA-2A,age,BMI and other clinical characteristics can reduce the rate of misdiagnosis and the rate of missed di-agnosis of T1DM.