This article discusses a case report of a Japanese woman in her 50s who developed glossitis, an inflammation of the tongue, along with autoimmune gastritis and pernicious anemia. The patient had a history of type 1 diabetes mellitus and Hashimoto's thyroiditis, and her glossitis worsened over time, leading to anemia. Gastrointestinal endoscopy revealed advanced atrophic gastritis primarily affecting the gastric corpus. The patient was diagnosed with Hunter's glossitis, pernicious anemia, and autoimmune gastritis, and was treated with vitamin B12 injections, resulting in improvement. The article emphasizes the importance of considering vitamin B12 deficiency and autoimmune gastritis in patients with glossitis and autoimmune thyroid diseases or type 1 diabetes mellitus. [Extracted from the article]