Background: C-peptide level is the most reliable factor evaluating the endogenous insulin secretion in patients with type 1 diabetes.
Objectives: The aim of the study was to investigate whether the age at onset, gender, presence of autoantibodies and ketoacidosis at diagnosis and insulin requirement, HbA1c levels could be applied to predict the C-peptide levels in the first year of type 1 diabetes in children.
Material and methods: 122 type 1 diabetic children, aged: 2-18 years (average 11.2), 44 female and 78 male were studied. Fasting C-peptide levels were examined by radioimmunoassay at diagnosis, after 10 days and after 1, 2, 3, 6 and 12 months of disease. At diagnosis islet cell antibodies (ICA) were detected by indirect immunofluorescence, antibodies to glutamic acid decarboxylase (GADA) and tyrosine phosphatase antibodies (IA2A) were measured by microradioimmunoprecipitation assay.
Results: Age at onset was positively correlated to C-peptide levels at each evaluated point of the disease (r=0.3-0.46, p<0.0001). One year after diagnosis C-peptide levels decreased in ICA(+) (p<0.04) and GADA(+) (p<0.002) patients but not in ICA(-) or GADA(-) children. There was no significant difference between the IA2A-positive and negative subjects in the C-peptide levels at 12th month of disease. C-peptide level was also related to ketoacidosis at diagnosis, insulin requirement and HbA1c levels during the first year of type 1 diabetes. Logistic regression analysis showed that male, younger age, low pH, higher HbA1c and insulin requirement at onset were associated with decreased C-peptide level at diagnosis (p<0.00002).
Conclusions: Young age, presence of diabetes-related autoantibodies and hyperglycaemia with severe acidosis at the disease onset may be associated with a decreased residual insulin secretion in type 1 diabetes in children.