Serum undercarboxylated osteocalcin correlates with hemoglobin A1c in children with recently diagnosed pediatric diabetes.

BackgroundOsteocalcin (OC), a hormone secreted by osteoblasts, improves beta-cell function in vitro and in vivo. We aimed to understand the relationship between OC and hemoglobin A1c (HbA1c) in pediatric diabetes. MethodsChildren (n=70; mean [SD] age=11.8years [3.1]; 34.3% non-Hispanic white, 46.3% Hispanic, 14.9% African-American, 4.5% other) newly diagnosed with diabetes (69.1% type 1 diabetes [T1D], 30.9% type 2 diabetes [T2D]) were studied. We collected clinical data at diagnosis and first clinical visit (V1) 9 weeks later (interquartile range [IQR]=7.9-12.0). Serum undercarboxylated OC (uOC) and carboxylated OC (cOC) were measured 7.0weeks (IQR 4.3-8.9) after diagnosis. ResultsMean [SD] uOC was 20.3 (19.6) ng/mL, cOC 29.7 [13.7] ng/mL and u/cOC 0.68 [0.81]. uOC, cOC, or u/cOC were not different by gender, race/ethnicity, age, diabetes type, BMI percentile, or random C-peptide, glucose or HbA1c at diagnosis. However, among 61 children with V1 within 4 months of diagnosis, uOC was higher in those with V1 HbA1c<7.5% (HbA1c<58mmol/mol) (uOC=33.1 [22.0]) compared with children with HbA1c7.5% (uOC=17.4 [2.3], P=.0004). The difference was larger among patients with T2D (34.6 and 4.7ng/mL, respectively, P=.0001) than T1D (32.2 and 19.3, P=.0169), and in males (36.1 and 17.4, P=.018) than females (27.6 and 17.3, P=.072). Analysis for u/cOC were similar while there were no differences in cOC. uOC was inversely correlated with HbA1c at V1 (Spearman's rho=-0.29, P=.02). ConclusionOur findings suggest that serum uOC is inversely related to HbA1c shortly after diagnosis of pediatric diabetes. This potentially modifiable factor of glucose metabolism warrants further studies.