Prevalence and phenotype characterstics of latent autoimmune diabetes in adulthood (LADA) and type 1 diabetes among young adults in Sri Lanka

Abstract

Sri Lankans are at high risk of diabetes. Knowledge of the aetiology is useful in disease prevention. Objectives: To determine the prevalence and clinico-metabolic characteristics of Glutamic Acid Decarboxylase Antibody (GAD) positive diabetes among young adult-onset subjects in Sri Lanka. Design, setting and methods: We recruited a sample of 1007 consecutive diabetic subjects 45 years (age of diagnosis 16 to 40 years). Clinical and metabolic characterization was performed. GAD antibodies were measured using a radioimmunoassay method. A titre >14U/L (WHO 97.5 percentile) was considered positive. LADA was diagnosed when subjects were GAD+ve, >30 years and insulin independent >6 months from diagnosis. Insulin resistance assessed using homeostatic model (HOMA-IR). Data were analysed using SPSS. Results: Mean age of the cohort was 36.7 years (± 5.8), males 42.3%. Overall 16% were insulin treated. GAD was positive in 5.4% (n=54) of our sample. The GAD titre had a significant negative correlation with the time of commencement of insulin (r=-0.22, p=0.006). The GAD+ve type 1 diabetes (TlDM) and LADA were 2.1% and 2.6% respectively. Among subjects with TlDM, LADA and type 2 diabetes (T2DM), BMI (kg/m2) [19.6, 22.2 and 25.0], fasting C-peptide (nmol/l) [0.08,0,52 and 0.65] and HOMAIR [0.28, 2.0 and 1.75] showed significant differences (p<0.001). Metabolic syndrome was present in 0%, 46% and 67.3% of the TlDM, LADA and T2DM subjects respectively (p<0.001). Conclusions: GAD positive diabetes is less prevalent among young adult diabetic subjects in Sri Lanka compared to T2DM. Subjects with LADA are phenotypicaly more related to T2DM than to TlDM.