Latent autoimmune diabetes in Tunisian adults (LADA): identification of autoimmune markers.

BACKGROUND: LADA or type 1.5 diabetes is a slowly progressive form of autoimmune diabetes of adults. The aim of this study is to evaluate the frequency of autoimmmune markers and to identify patients with LADA among diabetics diagnosed initially as having type 2 diabetes.

METHODS: Our study concerned 100 diabetics, aged between 31 and 77 years (age at onset > 30 years), with short term diabetes (duration < 6 years) and who required insulin therapy after 6 months from diagnosis of diabetes. All patients were screened for antibodies to Glutamic Acid Decarboxylase (GAD65), the Tyrosine Phosphatase (IA2) and Islet Cell antibodies (ICA).

RESULTS: Mean age of patients is 53 +/- 10.5 years. Mean age at onset of diabetes was 43.3 +/- 10 years. Insulin treatment required after 3.1 +/- 1.8 years. Positivity of at least one of the auto-antibodies was found in 78% of patients. ICA were detected in 48.5% of cases. IA2 and GAD antibodies were positive respectively in 42% and 18% of tested patients. There was no significant difference of gender. Anti-GAD positive patients had statistically significant higher initial fasting blood glucose and HDL-cholesterol serum (p = 0.01 and 0.007) than those with anti-GAD negative. Patients with anti-IA2 were characterized by more important frequency of autoimmune diseases and low rate of triglycerides. The frequency of macrovascular complications was lower in ICA positive diabetics than those with ICA negative. Patients initially diagnosed as type 2 diabetes may in many cases suffer from LADA. Auto-antibodies screening may be of interest to identify LADA at the earliest stage.

CONCLUSION: Frequency of type 1 diabetes in adults is underestimated. The identification of LADA may help to classify dabete and to indicate the moment of insulinotherapy.