Assessment of diabetes type, metabolic profiles, and treatment outcomes in adults presenting with hyperglycemia and undergoing testing for diabetes-specific autoantibodies

Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia and heterogeneous progression. DM is classified into four categories according to clinical, pathophysiological, and genetic characteristics: Type 1 DM, Type 2 DM, specific types due to other causes, and gestational DM. After confirming the diagnosis of diabetes, determining the diabetes type in the second step is important for diagnosis, treatment, and diabetes-related complications. In this study, we aimed to assess the diabetes type, metabolic status, and treatment outcomes in adult patients presenting with hyperglycemia for whom diabetes-specific autoantibodies were requested. A total of 350 patients who presented with hyperglycemia to the Endocrinology and Metabolism outpatient clinic of Pamukkale University Faculty of Medicine within the last 5 years and had diabetes-specific autoantibodies measured were included. The data were organized using SPSS, and patient information (age, sex, height, weight, presentation type—such as ketosis—family history, presence of autoimmune disease, serum fasting glucose, LFTs, TFTs, HbA1c, C-peptide, insulin, TSH, FT4, FT3, Anti-TPO, Anti-TG, iron, ferritin, B12, celiac antibodies, PTH, calcium, vitamin D, initial treatment, and 6- month treatment outcomes) was retrospectively reviewed from the data system. Of the 350 patients, 38.9% were female and 61.1% were male, with a mean age of 37.9 ± 10.7 years. A total of 68.6% of the patients were referred for diabetes classification. The majority (59.4%) were diagnosed with Type 2 DM. The proportion of patients followed with a Type 1 DM diagnosis was 29.7%. The rates of MODY and LADA were found to be 2% and 5.7%, respectively, in accordance with the literature. Autoimmune diseases such as hypothyroidism were more common in Type 1 DM patients, while hypertension was significantly more prevalent in Type 2 DM patients. Obesity was most common in Type 2 DM and dual DM groups, which was found to be statistically significant (p=0.001). Autoantibody positivity was more frequent in the Type 1 DM and dual DM groups (p<0.0001). Among patients diagnosed with LADA, GADA positivity was the highest at 85%. Regarding age at diagnosis, Type 1 DM patients were younger compared with those with Type 2 DM and LADA (p<0.0001). Patients with LADA had the highest mean age at diagnosis, with an average of 38.2 years. C-peptide levels were low in 92.3% of patients with Type 1 DM. Among MODY types identified in our study, MODY 2 was the most common, consistent with the literature. The multiple pathophysiological processes contributing to diabetes risk and progression vary among individuals, determining the phenotype and providing guidance for treatment. In both Type 1 and Type 2 DM, genetic and environmental factors may lead to progressive loss of β-cell mass and/or function, which clinically manifests as hyperglycemia. Once hyperglycemia develops, individuals with any type of diabetes are at risk for the same chronic complications, although the rate of progression may differ. Therefore, accurate classification is crucial for treatment and prevention of complications.