Endocrine Abstracts

Introduction: Classification of diabetes is challenging in some cases, especially in the presence of inaugural ketosis with a negative autoimmune laboratory test. The aim of our study is to determine the role of age, body mass index (BMI), and fasting plasma C-peptide (FCP) in the classification of diabetes.

Methods: This is a descriptive cross-sectional study that included 51 patients aged between 20 and 65 years hospitalized at the Endocrinology Department of the Military Hospital of Tunis for inaugural ketosis without a precipitating factor, with a duration of diabetes ranging from 6 months to 5 years. They underwent a metabolic biological assessment, an autoimmune laboratory test (anti-GAD65 + anti-IA2 antibodies), a fasting plasma C-peptide level. Our patients were divided into two groups: 31 patients with positive anti-GAD65 and/or anti-IA2 antibodies (AC+) and 20 patients with negative antibodies (AC-). Clinical and laboratory data were collected from medical records.

Results: Our population included 45 men and 6 women. Mean age was 34.3±10.8 years. A family history of type 1 diabetes and type 2 diabetes were present in 11.8 % and 60.8 % of the cases respectively. Hypertension, dyslipidemia, obesity, and thyroid disease were reported at 9.8 %, 17.6 %, 21.6 %, and 9.8 % respectively. The mean age at onset of diabetes in AC+ patients was 27.5±8.3 years and 36.3±10.1 years in AC-patients (P=0.002). The mean BMI was 24.5±3.4 Kg/m² in AC+ patients and 28.2±6.7 Kg/m² in AC-patients (P=0.024). FCP level was 0.6±0.7 ng/ml in AC+ patients and 1.7±1 ng/ml in AC-patients (P<10^-3). An FCP level greater than 0.8 ng/ml was positively correlated with the absence of autoimmunity (P<10^-3). Its area under the ROC curve was 0.850. Its sensitivity was 84% and specificity 85%.

Conclusion: The classification of diabetes is based on several factors including the age of onset, body mass index (BMI) and FCP levels. These markers along with the autoimmune status can be used to differentiate between type 1 and type 2 diabetes, and to adjust the therapeutic regimen.