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.

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.