C-Peptide and 24-Hour Urinary C-Peptide as Markers to Help Classify Types of Childhood Diabetes

Utility of Fasting C-Peptide for the Diagnostic Differentiation of Patients with Type 1, Type 2 Diabetes, MODY, and LADA

BACKGROUND

The prevalence of obesity has increased in patients with type 1 diabetes (T1D) and latent autoimmune diabetes of the adult (LADA), limiting the use of clinical features such as the body mass index for its differentiation with type 2 diabetes (T2D). Additionally, some patients with maturity-onset diabetes of the young (MODY) or LADA are misdiagnosed as having T2D. The evaluation of autoantibodies and genetic testing are not fully available. We aimed to evaluate the utility of a widely available and less expensive diagnostic tool such as C-peptide to differentiate between T1D, T2D, MODY, and LADA.

METHODS

Our study included 38 patients with T1D, 49 with T2D, 13 with MODY, and 61 with LADA. We recorded anthropometric measurements, biochemical profiles, and antidiabetic treatment and determined C-peptide, anti-GAD65, and anti-IA2 antibodies.

RESULTS

C-peptide concentration differed significantly among populations (T1D: 0.2 ng/mL; T2D: 2.4 ng/mL; MODY: 1.14 ng/mL; LADA: 1.87 ng/mL). Through a ROC curve, we observed that the C-peptide cut-off point of 0.95 ng/mL allows differentiation between T1D and T2D (sensitivity 82%, specificity 77%); 0.82 ng/mL between T1D and LADA (sensitivity 82%, specificity 77%); and 1.65 ng/mL between T2D and MODY (sensitivity 72%, specificity 72%).

CONCLUSIONS

C-peptide is useful for the diagnostic differentiation of patients with type 1, type 2 diabetes, MODY, and LADA.

Pediatric Type 2 Diabetes: Not a Mini Version of Adult Type 2 Diabetes

Pediatric type 2 diabetes mellitus (T2DM) is increasing in incidence, with risk factors including obesity, puberty, family history of T2DM in a first-degree or second-degree relative, history of small-for-gestational-age at birth, child of a gestational diabetes pregnancy, minority racial group, and lower socioeconomic status. The pathophysiology of T2DM consists of insulin resistance and progression to pancreatic beta-cell failure, which is more rapid in pediatric T2DM compared with adult T2DM. Treatment options are limited. Treatment failure and nonadherence rates are high in pediatric T2DM; therefore, early diagnosis and treatment and new pharmacologic options and/or effective behavioral interventions are needed.