2022 Volume 65 Issue 8 Pages 458-463
Glutamic acid decarboxylase (GAD) antibody, an islet-related autoantibody, is frequently found in the early stage of type 1 diabetes. Although the antibody titer decreases over time, it is uncommon for the antibody to disappear within months. We experienced the case of a patient with diabetes in which a GAD antibody test was positive during treatment for COVID-19 and negative thereafter. A 43-year-old man with type 2 diabetes was admitted to our hospital with COVID-19 pneumonia. He had an eight-year history of impaired glucose tolerance and had been treated only with diet and exercise therapy. On admission, a GAD antibody test was positive, but a second test seven months later was negative. The human leukocyte antigen (HLA) genotype was DRB1*09:01-DQB1*03:03, which is reported to be a disease-sensitive haplotype for type 1 diabetes in Japanese people. This case indicates that a GAD antibody test may be positive in patients with diabetes and COVID-19 and may become negative after recovery from COVID-19. In similar cases, physicians should be cautious when diagnosing the type of diabetes and should monitor the GAD antibody titer and insulin secretory capacity and ideally examine the HLA haplotype.
