Serum C-peptide and osteocalcin levels in children with recently diagnosed diabetes.
Background
We explored the association of C-peptide (marker of secreted insulin), proinsulin and proinsulin ⁄C-peptide ratio (PI/C) (markers of beta-cell endoplasmic reticulum [ER] stress) with undercarboxylated (uOC) and carboxylated osteocalcin (cOC) and their ratio (uOC/cOC) in children with recently diagnosed type 1 (T1D) or type 2 diabetes (T2D), and the correlation of these variables with partial remission (PR) in children with T1D.


Methods
Demographic and clinical data of children with new-onset diabetes (n = 68; median age = 12.2 years; 33.8% non-Hispanic White, 45.6% Hispanic/Latino, 16.2% African American and 4.4% other) were collected at diagnosis and during the first (V1), second (V2) and third clinical visits at 9.0, 32.0 and 175.7 weeks, respectively. Serum proinsulin, C-peptide, uOC and cOC values were measured 7.0 weeks after diagnosis. PR was defined as insulin dose-adjusted HbA1c (IDAA1c) ≤9.


Results
In children with new-onset T1D with DKA (33.3%) or T2D (29.4%), Spearman's correlation coefficient revealed a positive association between the C-peptide levels and both uOC and uOC/cOC ratio. In T1D (n = 48), both higher serum C-peptide levels and low PI:C ratio were associated with higher BMI percentile (β = 0.02, P = .001; β = -0.01, P = .02, respectively) and older age at diagnosis (β = 0.13, P = .001; β = -0.12, P = .001, respectively). Furthermore, in children with T1D, C-peptide levels at V1 correlated with IDAA1c ≤ 9 at V1 (P = .04).


Conclusion
C-peptide levels are associated with a higher uOC and uOC/cOC ratio in paediatric diabetes. In new-onset T1D children, older age and higher BMI were associated with lower beta-cell stress and higher preserved function, which was predictive of PR on follow-up.
['Sabek|Omaima M|OM|https://orcid.org/0000-0003-0919-0093', 'Redondo|Maria J|MJ|https://orcid.org/0000-0001-5871-4645', 'Nguyen|Duc T|DT|https://orcid.org/0000-0002-5059-4404', 'Beamish|Christine A|CA|https://orcid.org/0000-0002-0319-1346', 'Fraga|Daniel W|DW|', 'Hampe|Christiane S|CS|', 'Mulukutla|Surya N|SN|', 'Graviss|Edward A|EA|https://orcid.org/0000-0003-1024-5813', 'Gaber|A Osama|AO|']
osteocalcin diabetes paediatrics C‐peptide