Evaluation of Clinical, Laboratory and Immunological Characteristics in the Early Onset (Diagnosed Age < 30 Years...

The classification of early onset (< 30 years old) patients with diabetes mellitus (DM) as either type 1 diabetes (T1D) or type 2 diabetes (T2D) can be a challenge due to their similar overlapping phenotypes. In this study, we attempted to utilize various clinical and laboratory characteristics in combination with immunological factors in the blood to determine whether it would be possible to distinguish and more accurately characterize our patients as T2D.

Electronic medical records were evaluated to obtain information categorized as either early onset patients with DM (n = 102) and patients with T1D (n = 89). Using the stored serum from these patients, autoantibodies of anti-insulinoma associated 2 (IA2), anti-zinc transporter 8 (ZnT8) and anti-glutamic acid decarboxylase antibody (GAD) were measured.

In the clinical characteristics, early onset patients with DM (n = 102) were younger (31.7 ± 7.0 years old, P < 0.01), more overweight (28.1 ± 5.5 kg/m², P < 0.05), shorter duration of diabetes (10.4 ± 7.3 years, P < 0.01) and a more prevalent family history of diabetes (81%, P < 0.01) than patients with T1D. The laboratory values from early onset patients with DM exhibited lower glycated hemoglobin A1c (8.0 ± 2.1%, P < 0.01) and glucose levels (165 ± 73 mg/dL, P < 0.01) with conversely higher C-peptide levels (2.2 ± 1.2 ng/mL, P < 0.01). Measurements of immunological factors, demonstrated that the prevalence of anti-ZnT8 (2%) and anti-GAD antibody (2%) in early onset patients with DM was significantly lower (P < 0.01) compared to patients with T1D (13% for anti-ZnT8 and 38% for anti-GAD). The prevalence of anti-IA2 was not significantly different between early onset patients with DM (13%) versus patients with T1D (11%). In the multivariate logistic regression analysis, C-peptide level (B, 4.453; standard error [SE], 0.844; Wald, 27.808; P < 0.001) was the strongest independent factor to distinguish early onset patients with DM as T2D. After adjusting C-peptide level, family history of diabetes (B, 0.830; SE, 0.420; Wald, 3.909; P = 0.048), body mass index (BMI) (B, 0.111; SE, 0.039; Wald, 8.167; P = 0.004) and the relative negative status of anti-GAD (B, -2.041; SE, 0.597; Wald, 11.670; P < 0.001) were determining factors in our analyses.

In this study, our findings suggested that early onset patients with DM may be more accurately diagnosed as T2D if they have a compilation of elevated C-peptide levels, higher BMI, more prevalent history of familial diabetes and the absence of detecting anti-GAD antibodies.