Thyroid Autoimmunity at Onset of Type 1 Diabetes as a Predictor of Thyroid Dysfunction

Type 1 diabetes and autoimmune thyroid diseases (AITDs) often coexist in the same individual and in the same family. In the general population, AITD is more frequent in female subjects and prevalence increases with age. In diabetic patients, age and sex distributions are similar, but the prevalence is higher and increases with duration of the disease (1–3,4). Thyroid dysfunction can affect metabolic control in type 1 diabetes, and some studies (3) have shown a higher severity of diabetes when it is associated with AITD, although other studies (4) did not find these differences. Nevertheless, there is general agreement (5,6) on the utility of systematic screening of AITD in the type 1 diabetes population given its high prevalence, but procedure and frequency remain controversial. The aim of the present study was to determine the presence of thyroid autoantibodies at type 1 diabetes onset and its predictive capacity for the future development of thyroid dysfunction. Between September 1987 and January 1994, 204 patients were consecutively diagnosed with type 1 diabetes at our institution. One patient had developed primary hypothyroidism 3 years before the development of type 1 diabetes, 10 patients were not followed up after a few months from diagnosis, and thyroid autoimmunity at diagnosis was not determined in 17 patients. The remaining 176 patients were included in the study. The mean age at diabetes diagnosis was 24.4 ± 9.4 years, 65% were male …