Principles of diagnosis of latent autoimmune diabetes in adults (LADA)

Background . The purpose of this study was the evaluation of the prevalence of latent autoimmune diabetes in adults (LADA) and characteristics of its phenotype features. Material and methods . The subjects studied were 56 patients with the recent onset of diabetes type 2. All these patients were tested for the presence of autoantibodies ICA, GAD, IA-2. All patients were also characterized according to clinical symptoms preceeding the onset of the disease, age, BMI, concentrations of fasting blood glucose and C-peptide, HbA1c, the presence of glucosuria, ketonuria and ketoaccidosiss. ICA were measured by indirect immunofluorescence on cryostat sections of human pancreas of blood group O. GADab and IA-2ab were measured by a radioimmunoprecipitation assay, using in vitro transcribed and translated human protein labeled by S35 methionine. Results . The presence of at least one autoantibody was revealed in 14/56 patients. That allowed us to recognize LADA in these cases. The coexistence of two antibodies was observed in 3/14 patients. None of the patients had three examined autoantibodies. ICA were detected more frequently (11/14) than GADab and IA-2ab, which were found with the same frequency (3/14) (P < 0.004). LADA patients were younger than type 2 diabetic patients (median age 40.4 vs. 48.9 yrs; P < 0.009). BMI, HbA1c, FBG and C-peptide were similar in all patients. Conclusions . Among patients with diagnosed type 2 diabetes there is a group with autoimmune diabetes, called LADA. Phenotype similarity between diabetes type 2 and LADA (except for the age) makes the proper diagnosis impossible without more specific tests. The diagnosis of LADA is based on the presence of autoantibodies.