Objective: To investigate the correlation between serum C-peptide and in adult population, and establish the corresponding insulin values of serum C-peptide levels. Methods: Cross-sectional study. The clinical data of the adults who underwent physical examination in the Second Medical Center of PLA General Hospital from January 2017 to December 2021 were retrospectively included. The participants were divided into type 2 diabetes group, prediabetes group and normal plasma glucose group according to the diagnostic criteria for diabetes. The correlation between serum C-peptide and insulin was explored by Pearson correlation analysis, linear regression analysis, and nonlinear regression analysis, and the corresponding insulin values of serum C-peptide were established. Results: A total of 48 008 adults were enrolled, including 31 633 males (65.9%) and 16 375 females (34.1%), aged (50.1±9.9) years (18-89 years). There were 8 160 subjects (17.0%) with type 2 diabetes, 13 263 subjects (27.6%) with prediabetes, and 26 585 subjects (55.4%) with normal plasma glucose. The serum fasting C-peptide (FCP, M(Q1, Q3)] of the three groups were 2.76(2.18, 3.47), 2.54(1.99, 3.21) and 2.18(1.71, 2.79)μg/L, respectively. The fasting insulin [FINS, M(Q1,Q3)] of the three groups were 10.98(7.57, 16.09), 10.06(6.95, 14.47) and 8.43(5.86,12.12)mU/L, respectively. FCP was positively correlated with FINS (r=0.82), and 2 h postprandial C-peptide (2 h CP) was positively correlated with 2 h postprandial insulin (2 h INS) (r=0.84) (both P<0.001). FCP was linearly associated with FINS (R2=0.68), and 2 h CP was linearly associated with 2 h INS (R2=0.71) (both P<0.001). There was a power function correlation between FCP and FINS (R2=0.74), and 2 h CP and 2 h INS (R2=0.78) (both P<0.001). The results of the statistical analysis were similar in various glucose metabolism subgroups. Since the fitting degree of the power function model was higher than that of the linear model, the power function model was the best model. The power function equation was FINS=2.96×FCP1.32, and 2 h INS=1.64×(2 h CP)1.60, respectively. Multivariate linear regression analysis demonstrated that FCP was a related factor of FINS (R2=0.70, P<0.001) and 2 h CP was a related factor of 2 h INS (R2=0.73, P<0.001), after adjusting for related confounders. Conclusions: There was a power function correlation between FCP and FINS, 2 h CP and 2 h INS in adult population. The insulin values corresponding to C-peptide levels were established in the study.
目的： 探讨成年人群血清C肽与胰岛素的相关性，建立血清C肽对应的胰岛素值。 方法： 横断面研究。回顾性纳入2017年1月至2021年12月于解放军总医院第二医学中心行健康体检的成年人群的临床资料，根据糖尿病诊断标准将受试者分为2型糖尿病组、糖尿病前期组和正常血糖组。采用Pearson相关分析、线性回归分析和非线性回归分析等方法探讨血清C肽与胰岛素的相关性，并建立血清C肽对应的胰岛素值。 结果： 共纳入48 008名成年受试者，男31 633名（65.9%），女16 375名（34.1%），年龄（50.1±9.9）岁（18~89岁）；其中2型糖尿病组8 160例（17.0%），糖尿病前期组13 263例（27.6%），正常血糖组26 585名（55.4%）。3组血清空腹C肽［FCP，M（Q1，Q3）］分别为2.76（2.18，3.47）、2.54（1.99，3.21）和2.18（1.71，2.79）μg/L；3组空腹胰岛素［FINS，M（Q1，Q3）］分别为10.98（7.57，16.09）、10.06（6.95，14.47）和8.43（5.86，12.12）mU/L。FCP与FINS（r=0.82）、餐后2 h C肽（2 h CP）与餐后2 h胰岛素（2 h INS）（r=0.84）均呈正相关（P<0.001）。FCP与FINS（R2=0.68）、2 h CP与2 h INS（R2=0.71）均呈线性相关（P<0.001）。FCP与FINS（R2=0.74）、2 h CP与2 h INS（R2=0.78）均呈幂函数相关（P<0.001），不同糖代谢状态亚组分析结果相似。幂函数模型拟合度高于线性模型，幂函数模型为最佳模型，幂函数方程分别为FINS=2.96×FCP1.32、2 h INS=1.64×（2 h CP）1.60。多因素线性回归分析显示，在调整相关混杂因素后，FCP是FINS（R2=0.70，P<0.001）的相关因素，2 h CP是2 h INS（R2=0.73，P<0.001）的相关因素。 结论： 成年人群FCP与FINS、2 h CP与2 h INS均呈幂函数相关。本研究建立血清C肽水平分别对应的胰岛素值。.