Clinical approach to the differential diagnosis between immune-mediated diabetes and type 2 diabetes in adult patients

Background
IDM/LADA is late-manifesting immune-mediated diabetes diagnosed in patients over 30 years of age. It is estimated to account for 5–10% of diabetes cases in adults.

Objectives
The aim of the study was to identify the parameters implying the diagnosis of immune-mediated diabetes among adults with new-onset diabetes.

Material and methods
Study included patients 30–50 years of age with new-onset diabetes, hospitalised between 2014 and 2019 in the Diabetology Department. Medical history, hyperglycaemia symptoms, comorbidities, anthropometric measurements and laboratory tests were analysed. The exclusion criterion was a history of pancreatitis.

Results
We analysed a group of 182 patients (mean age 38.1 ± 5.1). IDM/LADA was diagnosed in 78 (43%) patients. In the subgroup of subjects 30–35 years of age, IDM/LADA patients constituted 50.08%, whereas in the 36–50 years of age group, this constituted 38.65% of all the patients. The IDM/LADA patients were younger, had a lower body mass and BMI, noticed symptoms of diabetes before hospitalisation and more often had other autoimmune disorders. Thier C-peptide concentrations were nearly three times lower, while T2DM patients had a higher concentration of total cholesterol and triglycerides and more frequently had arterial hypertension (all p < 0.05). Testing for one antibody (GADA) allows one to diagnose 83% of IDM/LADA cases. Furthermore, determination of both GADA and ICA resulted in diagnosing autoimmune diabetes in 97% of all the patients.

Conclusions
With a measurement of C-peptide concentration and GADA detection, we could diagnose IDM/LADA with 89% sensitivity. Moreover, the inclusion of clinical features increased the sensitivity up to 93.5%. Considering the age criterion, there was no significant difference between the groups of patients with IDM/LADA.