ESPE Abstracts

Background: Assessment of beta-cell function in type 1 diabetes (T1D) has important implications in both clinical and research settings. Studies are limited by the lack of adjustments demonstrating the extent to which puberty influences C-peptide levels. The aim of this study was to evaluate the influence of pubertal stage as well as age and body mass index (BMI) on multiple C-peptide measures at T1D diagnosis.

Methods: This study included 275 consecutive children aged 1-18 years with newly recognized T1D. Fasting, prandial, and area under the curve (AUC) C-peptide, estimated using fasting and prandial C-peptide levels, were analyzed. In addition, C-peptide increment was also evaluated. Univariate and multivariable linear regression models were utilized.

Results: Median age at diagnosis was 8.4 (1.1-17.3) years, and mean BMI standard deviation score (SDS) was -0.4±1.5. Of the patients, 66% were prepubertal. Median fasting and prandial C-peptide levels at diagnosis were 0.26 (0.05-1.4) ng/ml and 0.43 (0.05-3) ng/ml, respectively. Fasting C-peptide was almost perfectly correlated with prandial C-peptide (rs=0.80, P<0.001). Fasting, prandial, and AUC C-peptide were positively related with BMI SDS, age, and pubertal stage at diagnosis (P<0.001 for all). All the associations persisted when the variables were included as independent variables in regression models (P=0.022 to <0.001). BMI SDS, age, and pubertal stage together explained 19-25% of the variance of C-peptide measures. There was also a positive correlation between C-peptide increment and both age and pubertal stage (rs=0.28, P<0.001 and rs=0.35, P<0.001, respectively).

Conclusions: The findings presented here have implications for the clinical assessment of young individuals with diabetes and clinical trials evaluating interventions for preserving beta-cell function in patients with new-onset T1D. While age and BMI at diagnosis are key variables associated with beta-cell function, our data set sets the stage for a greater understanding of the disease process with additional findings regarding puberty.