Factors Associated with C-peptide Levels after Diagnosis in Children with Type 1 Diabetes Mellitus.

C-peptide is the best indicator of endogenous insulin secretion in patients with diabetes. This study investigated the relationship between C-peptide levels and clinical/laboratory parameters of children with type 1 diabetes mellitus (T1DM), as measured at 6-month intervals after diagnosis. We retrospectively reviewed the data of 34 children with newly diagnosed T1DM. The study subjects were subdivided into a rapid progression group with C-peptide levels <0.6 ng/mL at 36 months (n=27; Group A) and a slow progression group with C-peptide levels >0.6 ng/mL at 36 months (n=7; Group B). Patients in Group A had a younger mean age at diagnosis (A: 9±4.3 years vs. B: 13.6±3.6 years; p=0.013) and lower body mass index (BMI) (A: 15.5±2.5 kg/m2 vs. B: 18.7±3.3 kg/m2 ; p=0.035). There were fewer asymptomatic patients with glucosuria in Group A, with these patients showing more severe symptoms, such as diabetic ketoacidosis (p=0.035), than those in Group B. Group A also had lower initial C-peptide levels (A: 0.5±0.46 ng/mL vs. B: 1.87±1.08 ng/mL; p=0.001). There were no significant intergroup differences in sex, family history, baseline hemoglobin A1c (HbA1c), potential of hydrogen (pH), autoantibodies or serum insulin. Simple correlation analyses showed that C-peptide levels were correlated with age and BMI, but not with pH, insulin, or HbA1c. Younger patients, who had a lower BMI, significant symptoms with complications, and/or a low initial C-peptide level, tended to show a rapid rate of decrease in C-peptide levels. Early intensive insulin therapy to preserve beta-cell function should be considered in these groups.