Endocrine Abstracts

Introduction: An increased risk of thyroid disease (TD) has been described in patients with type 1 diabetes (DM1) with respect to the general population. The objective is to establish the incidence and characterize the differences in patients who develop TD in relation to the debut of DM1 (previous, concurrent or a posteriori).

Materials and methods: Retrospective study of 1126 patients followed up in Endocrinology consultations in Navarra. Three types of TD were differentiated: hyperthyroidism (HI), hypothyroidism (HO) and autoimmune thyroid disease with normo function (AT). Clinical and analytical variables were analyzed. Comparison between the medians of the groups was performed using the Mann Whitney U test. Differences between categorical variables were analyzed using the χ2 test.

Results: The study population included 669 men (59.3%) and 459 women (40.7%), with a mean age at debut of 20 years and a mean follow-up of 11.4 years (7.6 sd). A total of 300 (26.6%) developed thyroid disease. The analysis of the 32 that already had TD before the onset of DM1 (8 HI, 21 HO, 3 AT) revealed thar women, gastric autoimmunity and younger patients had a higher risk of developing TD. 87 patients presented concurrent TD (10 HI, 40 HO, 37 AT) at the onset of DM1. Female gender, debut over 45 years and positive gastric autoimmunity was also more frequent in those 181 patients that developed TD at follow up (16 HI, 102 HO, 63 AT) of the DM1.

Conclusion: In the population studied, the cumulative incidence of TD in the follow-up of patients with DM1 was high, with hypothyroidism predominating. There are different clinical and analytical variables that can predict which risk groups have a greater predisposition to develop TD before, at the onset or after the diagnosis of DM1. The factors to be taken into account that affect a different susceptibility to develop TD are gender, age at DM1 debut, thyroid autoimmunity and gastric autoimmunity. Although confirmation is required in future studies, they may be indicative for closer surveillance.