Case Report: Onset of Type 1 Diabetes Mellitus in a Patient With Ulcerative Colitis and Sjogren's Syndrome Under Euthyroid Hashimoto's Thyroiditis.

Type 1 diabetes mellitus (T1DM) is often complicated with some other autoimmune disorders. The complication of various autoimmune disorders is known as autoimmune polyglandular syndrome (APS). Once autoimmune thyroid disease develops, various autoimmune diseases can also occur. Such phenomena are classified as APS types 3A to 3D. In this report, we show the onset of T1DM in a patient with ulcerative colitis (UC) and Sjogren's syndrome. The most important and interesting point in this case is that, if we did not check her thyroid-associated antibodies, we could not have diagnosed her as APS. From the data of this case, we assumed that the patient suffered from APS type 3A, 3B, and 3D variants. This case pointed out very clearly the importance of testing for thyroid-associated antibodies under various autoimmune disease conditions even if the thyroid hormone levels are euthyroid. Moreover, based on the strong linkage between inflammatory bowel disease and T1DM and the compatibility with both T1DM and APS type 3, we think it is possible that Hashimoto's disease is present under complicated conditions together with UC and T1DM. It would be important to repeatedly check for thyroid-associated antibodies even in euthyroid patients, especially under various autoimmune disease conditions.