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Updated: Aug 16, 2026

A Method for Mouse Pancreatic Islet Isolation and Intracellular cAMP Determination
Published on: June 25, 2014
[Replacement of insulin by fasting C-peptide in modified homeostasis model assessment to evaluate insulin resistance
Xia Li1, Zhi-Guang Zhou, Hai-Ying Qi
1Department of Endocrinology, Second Xiangya Hospital, Central South University, Changsha, China.
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.
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