ESPE Abstracts

Background: C-peptide, an indicator of own insulin production, is usually very low in patients with type 1 diabetes (T1D).

Objective and hypotheses: The aim of the study was to evaluate C-peptide levels in children and adolescents and young adults with T1D and to correlate them with glycemic control.

Method: Fasting C-peptide levels were measured with RIA, in 118 children, adolescents and young adults (60 females, mean age 13.3 S.D. (5.9) years, median disease duration 5.8 years (range 0–25 years)). C- peptide was measured after a median period of 1.3 years (range 0–22). HbA1c, daily insulin requirements, height, and weight anti GAD65 anti IA2 autoantibodies were evaluated. Out of 118 subjects 65 were on continuous insulin infusion and 53 on a multiple injection regimen.

Results: C-peptide was measured in 56 subjects <1 year after diagnosis, in 27 1–5 years and in 34 >5 years and found increased (>3 ng/ml) in 53% of subjects, even when measured >5 years after diagnosis vs 80.3% <1 year and 77.7% between 1 and 5 years (P=0.014). Out of 83 subjects with C-peptide >0.3 ng/ml 38.5% were <5 years old at T1D diagnosis, 37.3% between 5 and 10 and 24% >10 years old (P=NS). HbA1c was not different between two groups of C-peptide (>0.3 or <0.3 ng/ml) after exclusion of HbA1c values at the time of diagnosis. Furthermore there was no difference in age, daily insulin requirements and BMI between the two groups, however, subjects with C-peptide <0.3 ng/ml had longer disease duration vs those with higher C-peptide (P=0.004). Linear regression analysis showed no correlation between HbA1c levels at the time of last visit and previous C-peptide levels. Out of 19 subjects with negative autoantibodies 13 had higher C-peptide values.

Conclusion: C-peptide levels higher than 0.3 ng/ml can be found in subjects with T1D, even years after diagnosis. Nevertheless these higher values do not seem to affect significantly glycaemic control.