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The influence of body mass index and age on C-peptide at the diagnosis of type 1 diabetes in children who participated in the diabetes prevention trial-type 1.

Citation
Sosenko, J. M., et al. “The Influence Of Body Mass Index And Age On C-Peptide At The Diagnosis Of Type 1 Diabetes In Children Who Participated In The Diabetes Prevention Trial-Type 1.”. Pediatric Diabetes, pp. 403-409.
Center Indiana University University of Washington
Multicenter
Multicenter
Author Jay M Sosenko, Susan Geyer, Jay S Skyler, Lisa E Rafkin, Heba M Ismail, Ingrid M Libman, Yuk-Fun Liu, Linda A DiMeglio, Carmella Evans-Molina, Jerry P Palmer
Keywords C-peptide, age, Body mass index, Children, type 1 diabetes
Abstract

BACKGROUND/OBJECTIVE: The extent of influence of BMI and age on C-peptide at the diagnosis of type 1 diabetes (T1D) is unknown. We thus studied the impact of body mass index Z-scores (BMIZ) and age on C-peptide measures at and soon after the diagnosis of T1D.

METHODS: Data from Diabetes Prevention Trial-Type 1 (DPT-1) participants <18.0 years at diagnosis was analyzed. Analyses examined associations of C-peptide measures with BMIZ and age in 2 cohorts: oral glucose tolerance tests (OGTTs) at diagnosis (n = 99) and mixed meal tolerance tests (MMTTs) <6 months after diagnosis (n = 80). Multivariable linear regression was utilized.

RESULTS: Fasting and area under the curve (AUC) C-peptide from OGTTs (n = 99) at diagnosis and MMTTs (n = 80) after diagnosis were positively associated with BMIZ and age (P < .001 for all). Associations persisted when BMIZ and age were included as independent variables in regression models (P < .001 for all). BMIZ and age explained 31%-47% of the variance of C-peptide measures. In an example, 2 individuals with identical AUC C-peptide values had an approximate 5-fold difference in values after adjustments for BMIZ and age. The association between fasting glucose and C-peptide decreased markedly when fasting C-peptide values were adjusted (r = 0.30, P < .01 to r = 0.07, n.s.).

CONCLUSIONS: C-peptide measures are strongly and independently related to BMIZ and age at and soon after the diagnosis of T1D. Adjustments for BMIZ and age cause substantial changes in C-peptide values, and impact the association between glycemia and C-peptide. Such adjustments can improve assessments of β-cell impairment at diagnosis.

Year of Publication
2018
Journal
Pediatric diabetes
Volume
19
Issue
3
Number of Pages
403-409
Date Published
12/2018
ISSN Number
1399-5448
DOI
10.1111/pedi.12609
Alternate Journal
Pediatr Diabetes
PMID
29171129
PMCID
PMC5918232
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