C-peptide Index under Non-fasting Conditions Can Predict the Likelihood of Future Insulin Therapy in Outpatients with Type 2 Diabetes Mellitus Not Receiving Insulin at Baseline.

Journal: Internal medicine (Tokyo, Japan)
Published Date: Nov 20, 2025

Abstract

Objective This study aimed to develop a clinical model in which the C-peptide index (CPI) under non-fasting conditions can predict future insulin therapy in patients with type 2 diabetes mellitus (T2DM). Methods This was a single-center retrospective study. We analyzed the correlation between non-fasting CPI and future insulin therapy in 464 patients who T2DM not receive insulin therapy who attended our clinic and were evaluated for non-fasting CPI on an outpatient basis. We used machine learning as an adjunct method to create a clinical model to predict future insulin therapy. Results At the end of the observation period, 22 participants remained on insulin therapy (continuous insulin therapy group: CIG), and 442 were not on insulin therapy (without insulin therapy group: WIG). HbA1c and serum creatinine (Cre) were significantly higher in the CIG than in the WIG (p<0.001 and p=0.045, respectively). The non-fasting CPI was lower in the CIG than in the WIG (p<0.001). The cutoff value of non-fasting CPI to predict the need of future insulin therapy was 1.62 (sensitivity 40.9%, specificity 90.7%), and the cutoff value to indicate the low possibility of future insulin therapy was 3.11 (sensitivity 90.1%, specificity 48.9%). A clinical model was created to predict future insulin therapy by machine learning using the Easy Ensemble Classifier method with non-fasting CPI, HbA1c, and Cre as features (accuracy, 78.5%; area under the ROC curve 0.86, false positive rate, 18.2%; false negative rate, 22.2%). Conclusion CPI under non-fasting conditions can predict the likelihood of future insulin therapy in outpatients with T2DM.

Authors

  • Yuichiro Iwamoto
    Research Center for Advanced Science and Technology, The University of Tokyo, Meguro 4-6-1, Shibuya, Tokyo, Japan.
  • Tomohiko Kimura
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Yuichi Morimoto
    Department of Pediatrics, Kindai University, Osakasayama, Japan.
  • Yuto Kimura
    Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan; Radiation Oncology Center, Ofuna Chuo Hospital, Kamakura, Japan.
  • Masahiro Komi
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Japan.
  • Yuki Watanabe
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Japan.
  • Taku Sasaki
    Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan.
  • Masato Kubo
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Japan.
  • Erina Nakao
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Japan.
  • Yui Okamoto
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Japan.
  • Toshitomo Sugisaki
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Kazunori Dan
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Hideyuki Iwamoto
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Junpei Sanada
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Yoshiro Fushimi
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Yukino Katakura
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Masashi Shimoda
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Shuhei Nakanishi
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Tomoatsu Mune
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Kohei Kaku
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.
  • Hideaki Kaneto
    Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Kurashiki, Japan.

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