Levels of C-peptide, body mass index and age, and their usefulness in classification of diabetes in relation to autoimmunity, in adults with newly diagnosed diabetes in Kronoberg, Sweden

Research output: Contribution to journalArticle


Objective: C-peptide is a main outcome measure in treatment trials of diabetes. C-peptide also has a role in the classification of diabetes, which is often difficult in adults and this is also increasingly recognised in adolescents and elders. Aim: We aimed to describe the levels of C-peptide in relation to age and body mass index (BMI) in a large population-based cohort of adults with newly diagnosed diabetes and compare the capabilities of C-peptide, age and BMI to discriminate between autoimmune and non-autoimmune diabetes. Subjects and methods: Blood samples from 1180 patients were analysed regarding islet cell antibody, glutamic acid decarboxylase antibody and fasting C-peptide (FCP). Receiver operating characteristics (ROC) curves were analysed to check the ability of age, BMI and C-peptide to discriminate between autoantibody-positive (Ab(+)) and -negative (Ab(-)) diabetes. Results: Mean FCP was 0.73 +/- 0.5 (range 0.13-1.80) nmol/l in the Ab(+) and 1.42 +/- 0.9 (range 0.13-8.30) nmol/l in the Ab(-). FCP was 0.02 nmol/l higher per year increase in age at diagnosis of diabetes. Mean BMI was 26.0 +/- 4.8 (range 18.0-39.0) kg/m(2) in the Ab(+) and 28.9 +/- 5.3 (range 15.5-62.6) kg/m(2) in the Ab(-). FCP increased with age also within each BMI group. The highest area under the curve (AUC) in the ROC analysis was found for C-peptide, followed by age and BMI (0.78, 0.68 and 0.66 respectively). Conclusions: At diagnosis of diabetes, C-peptide was superior to age and BMI in discriminating between autoimmune and non-autoimmune diabetes. C-peptide increased significantly with BMI and age, latter also within each BMI group. Most of the adults had normal or high levels of C-peptide at presentation of diabetes among the autoimmune patients.


  • Maria Thunander
  • Carina Torn
  • Christer Petersson
  • Birger Ossiansson
  • Jan Fornander
  • Mona Landin-Olsson
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Endocrinology and Diabetes
Original languageEnglish
Pages (from-to)1021-1029
JournalEuropean Journal of Endocrinology
Issue number6
Publication statusPublished - 2012
Publication categoryResearch

Related research output

Thunander, M., 2011, Medicine (Lund). 153 p.

Research output: ThesisDoctoral Thesis (compilation)

View all (1)