Preserved C-peptide levels in overweight or obese compared with underweight children upon diagnosis of type 1 diabetes mellitus

PURPOSE: We hypothesized that overweight or obese children might develop type 1 diabetes mellitus (T1DM) early despite residual beta-cell function. Factors independently associated with preservation of C-peptide level were analyzed. METHODS: We retrospectively reviewed the medical data of 135 children aged 2.1-16.5 years with autoimmune T1DM. Body mass index (BMI), pubertal stage, and glycosylated hemoglobin (HbA1c) and C-peptide levels were evaluated. Patients were assigned to underweight (22.2%), normal weight (63.7%), and overweight or obese (14.1%) groups according to their BMI. RESULTS: Preservation of serum C-peptide levels (≥0.6 ng/mL) was found in 43.0% of subjects. With increasing BMI, the proportions of children with preserved C-peptide levels increased from 33.3% to 41.9% to 63.2%, with marginal significance (P=0.051). Interaction analysis indicated no effect of BMI score on age at onset associated with serum C-peptide levels. The lower the C-peptide level, the younger the age of onset (P<0.001), after adjustment for BMI z-score and HbA1c level. However, no significant relationship between BMI z-score or category and onset age was evident. Upon multivariate-adjusted modeling, the odds that the C-peptide level was preserved increased by 1.2 fold (P=0.001) per year of life, by 3.1 folds (P=0.015) in children presenting without (compared to with) ketoacidosis, and by 5.0 folds (P=0.042) in overweight or obese (compared to underweight) children. CONCLUSION: Overweight or obese children had slightly more residual beta-cell function than did underweight children. However, we found no evidence that obesity temporally accelerates T1DM presentation.