用空腹C肽代替胰岛素改良Homa公式评价胰岛素抵抗和胰岛β细胞功能

Replacement of insulin by fasting C-peptide in modified homeostasis modelassessment to evaluate insulin resistance and islet β cell function

目的 :探讨用C肽代替Homa公式的胰岛素来评价胰岛素抵抗和胰岛 β细胞功能的可能性。方法 :对2 1例健康对照进行口服糖耐量试验 (OGTT) ,抽空腹、服糖后 30 ,6 0 ,1 2 0min血测血糖、胰岛素和C肽。分别以C肽×血糖、C肽 / (空腹血糖 - 3.5 )为自变量 ,以Homa公式计算的胰岛素抵抗指数 (Homa IR)和胰岛功能指数(Homa islet)为因变量拟合多元逐步回归方程 ,得到改良的Homa(CP)公式。对两公式的相关性和差异进行比较。结果 :拟合的以C肽来评价胰岛素抵抗和胰岛功能的公式分别为 :Homa IR (CP) =1 .5 +空腹血糖×空腹C肽 /2 80 0 (方程F =5 .5 1 1 ,P =0 .0 2 9) ;Homa islet (CP Normal) =0 .2 7×空腹C肽 / (空腹血糖 - 3.5 ) +5 0 ;Homa islet(CP DM ) =0 .2 7×空腹C肽 / (空腹血糖 - 3.5 ) (F =2 1 2 .96 1 ,P =0 .0 0 0 )。Homa IR(CP)与Homa IR ,Homa islet(CP)与Homa islet的相关性良好 (相关系数分别为 0 .6 89和 0 .788,P =0 .0 0 0 )。用两个公式分别计算所得的糖尿病患者的胰岛功能和胰岛素抵抗指数无统计学意义。结论 :空腹C肽可代替Homa公式中的胰岛素来评价糖尿病和健康者的胰岛素抵抗和胰岛功能 。

Objective To investigate the possibility of using C peptide to replace insulin in homeostasis model assessment (Homa) to evaluate insulin resistance and islet β cell function. Methods Oral glucose tolerance test (OGTT) was performed in 21 normal subjects, whose venous blood was drawn before taking glucose and 30, 60, 120 minutes after taking glucose. Insulin and C peptide were determined with radioimmune assay. Homa indices of insulin resistance and islet β cell function were calculated. Multiple stepwise linear regression model of insulin resistance was measured using C peptide×blood glucose as independent variables and Homa IR was used as the dependent variable, while the model of islet β cell function was determined using C peptide/(fasting blood glucose-3.5) as the independent variable and Homa islet as the dependent variable.Results The modified Homa formula were:Homa IR(CP)=1.5+fasting blood glucose×fasting C peptide /2800( F=5.511,P=0.029) , Homa islet (CP Normal) = 0.27 × fasting C peptide /(fasting blood glucose-3.5)+ 50,and Homa islet (CP DM)=0.27×fasting C Peptide /(fasting blood glucose-3.5)( F=212.961, P =0.000),respectively. The modified Homa IR(CP) and Homa IR,Homa islet (CP) and Homa islet were highly correlated ( r =0.689 and r=0.788; all P =0.000 ). Using Homa and modified Homa formula to evaluate the insulin resistance and islet β cell function both in the normal and diabetic subjects was similar.Conclusion Fasting C peptide can substitute insulin in Homa model to assess insulin resistance and islet β cell function. The modified homeostasis model assessment may be applied in the diabetics using exogenous insulin.