Residual β-Cell Function 3–6 Years After Onset of Type 1 Diabetes Reduces Risk of Severe Hypoglycemia in Children and Adolescents

OBJECTIVE To determine the prevalence of residual β-cell function (RBF) in children after 3-6 years of type 1 diabetes, and to examine the association between RBF and incidence of severe hypoglycemia, glycemic control, and insulin requirements. RESEARCH DESIGN AND METHODS A total of 342 children (173 boys) 4.8-18.9 years of age with type 1 diabetes for 3-6 years were included. RBF was assessed by testing meal-stimulated C-peptide concentrations. Information regarding severe hypoglycemia within the past year, current HbA1c, and daily insulin requirements was retrieved from the medical records and through patient interviews. RESULTS Ninety-two children (27%) had RBF >0.04 nmol/L. Patients with RBF <0.04 nmol/L were significantly more likely to have severe hypoglycemia than patients with RBF >0.04 nmol/L (odds ratio, 2.59; 95% CI, 1.10-7.08; P < 0.03). HbA1c was significantly higher in patients with RBF <0.04 nmol/L compared with patients with RBF >0.04 nmol/L (mean, 8.49 ± 0.08% [69.3 ± 0.9 mmol/mol] vs. 7.92 ± 0.13% [63.1 ± 1.4 mmol/mol]; P < 0.01), and insulin requirements were significantly lower in patients with RBF >0.2 nmol/L (mean ± SE: 1.07 ± 0.02 vs. 0.93 ± 0.07 units/kg/day; P < 0.04). CONCLUSIONS We demonstrated considerable phenotypic diversity in RBF among children after 3-6 years of type 1 diabetes. Children with RBF are at lower risk for severe hypoglycemia, have better diabetes regulation, and have lower insulin requirements compared with children without RBF. There appears to be a lower limit for stimulated RBF of ∼0.04 nmol/L that confers a beneficial effect on hypoglycemia and metabolic control.