C-peptide index at 2 h post-meal is a useful predictor of endogenous insulin secretory capacity and withdrawal from insulin therapy in subjects with type 2 diabetes.

Aims: To evaluate the correlation between C-peptide index (CPI) at 2 h post-meal and endogenous insulin secretory capacity and to develop clinical models to predict the possibility of withdrawal from insulin therapy in patients with type 2 diabetes.
Method: This was a single-centre retrospective study of patients with type 2 diabetes admitted to our hospital. Patients were divided into a withdrawal group (n = 72) and a non-withdrawal group (n = 75) based on whether they were able to withdraw from insulin therapy at discharge, and the correlation between CPI at 2 h after meal and diabetes-related parameters was evaluated. In addition, we created two clinical models to predict the possibility of withdrawal from insulin therapy using machine learning.
Results: The glycated haemoglobin values of the study participants were 87.8 ± 22.6 mmol/mo. The CPI at 2 h post-meal was 1.93 ± 1.28 in the non-withdrawal group and 2.97 ± 2.07 in the withdrawal group (p < 0.001). CPI at 2 h post-meal was an independent predictor of withdrawal from insulin therapy. In addition, CPI at 2 h post-meal was a better predictor than fasting CPI. Six factors associated with insulin therapy withdrawal (age, duration of diabetes, creatinine, alanine aminotransferase, insulin therapy until hospitalization, and CPI at 2 h post-meal) were used to generate two clinical models by machine learning. The accuracy of the generated clinical models ranged from 78.3% to 82.6%.
Conclusion: The CPI at 2 h post-meal is a clinically useful measure of endogenous insulin secretory capacity under non-fasting conditions.
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