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

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21例健康对照进行口服糖耐量试验（OGTT），抽空腹、服糖后30，60，120 min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/2800（方程F=5.511, P=0.029）；Homa-islet (CP-Normal)=0.27×空腹C肽/(空腹血糖-3.5)+50；Homa-islet (CP-DM)=0.27×空腹C肽/ (空腹血糖-3.5)（F=212.961,P=0.000）。 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0.689和0.788，P=0.000）。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，可能适用于使用外源性胰岛素的糖尿病患者。

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

OBJECTIVE: To investigate the possibility of using C-peptide to replace insulin in homeostasis model assessment (Homa) to evaluate insulin resistance and islet beta 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 beta cell function were calculated. Multiple stepwise linear regression model of insulin resistance was measured using C-peptide x blood glucose as independent variables and Homa-IR was used as the dependent variable, while the model of islet beta cell function was determined using C-peptide/(fasting blood glucose - 3.5) as the independent variable and Homaislet as the dependent variable. RESULTS: The modified Homa formula were: Homa-IR (CP) = 1.5 + fasting blood glucose x fasting C-peptide/2800 (F = 5. 511, P = 0.029), Homa-islet (CP-Normal) = 0.27 x fasting C-peptide /(fasting blood glucose - 3.5) + 50, and Homa-islet (CP-DM) = 0.27 x 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 beta 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 beta cell function. The modified homeostasis model assessment may be applied in the diabetics using exogenous insulin.