LADA prevalence estimation and insulin dependency during follow-up

Abstract

Background Latent autoimmune diabetes in adults (LADA) is a form of autoimmune-mediated diabetes in adults, usually defined by GAD autoantibody positivity. Few epidemiological surveys on LADA in Asians did not come to a conclusive answer regarding prevalence and incidence, because of different criteria used in patient ascertainment. Methods We estimated LADA prevalence in a recent type 2 diabetes cohort by the positivity of circulating autoantibodies to pancreatic islet cell antigens (GAD, IA-2 and zinc transporter 8 (ZnT8)) applying a comparable Caucasian criteria. We then observed the development of insulin dependency prospectively for 36 months. Results Applying the European NIRAD LADA group criteria, we found a high prevalence of LADA (4.4%) in Korean patients with phenotypic type 2 diabetes. This high prevalence of LADA in Korea is noteworthy since the previous population-based LADA prevalence survey reported low prevalence (1.7%). When we consider the low-titre GAD antibodies and the low prevalence of multiple autoantibodies, however, increased LADA prevalence does not necessarily mean increase in future insulin dependency. After 36 months of follow-up, only 3 of 39 patients who were initially classified as LADA have become insulin-dependent. Those three were all positive for multiple autoantibodies (GAD, IA-2 and zinc transporter 8 antibody). Other features of insulin secretion or insulin resistance did not determine future insulin necessity. Conclusions Although the LADA prevalence estimated by anti-GAD positivity appeared to increase, the true insulin dependency evidenced by multiple antibody positivity did not increase in Korea.