An Adult Case of Diabetes With High Levels of GAD Antibodies Without Insulin Deficiency for More Than 10 Years.

Latent autoimmune diabetes in adults (LADA) or slowly progressive insulin-dependent diabetes mellitus (SPIDDM) is a form of autoimmune diabetes characterized by autoimmune destruction of pancreatic beta cells, leading to deficient insulin secretion. Here, we report a case of diabetes and obesity in a 56-year-old woman. She was diagnosed with severe obesity, impaired glucose tolerance (IGT), and a positive antiglutamic acid decarboxylase antibody (GADA) test result at the age of 39 years. She developed diabetes 7 years later, meeting the diagnostic criteria for SPIDDM (probable). Despite high GADA levels, her endogenous insulin secretion has been preserved for over a decade. GADA has been regarded as a marker of autoimmune destruction of pancreatic beta cells, and high levels of GADA are considered a risk factor for future insulin deficiency. However, the role of GADA in its pathogenesis remains unclear. GADA is not a specific indicator of autoimmune diabetes, as it is also positive for autoimmune diseases such as autoimmune thyroid diseases (AITDs) and stiff-person syndrome. Therefore, a positive GADA test alone is not sufficient to predict insulin deficiency in an individual case, even if the titer is high. In the early stages, autoimmune diabetes presents clinical features similar to those of type 2 diabetes, particularly obesity. Although insulin therapy is often started early in the treatment of autoimmune diabetes, as the consensus statement indicates, when endogenous insulin secretion is preserved and the risk of insulin deficiency is low, efforts should be made to prevent body weight gain and the development of cardiovascular diseases (CVD) by following treatment guidelines for type 2 diabetes, with the exception of the use of sulfonylurea agents.