Clinical presentation and early course of type 1 diabetes in patients with and without thyroid autoimmunity.

OBJECTIVE: To evaluate the prevalence of thyroid autoimmunity (TAI) in patients with recent-onset type 1 diabetes and to determine the influence of TAI on the clinical presentation and evolution of type 1 diabetes. RESEARCH DESIGN AND METHODS: We studied 111 newly diagnosed type 1 diabetes patients > 13 years old. The diagnosis of TAI was based on medical history and measurement of thyroid peroxidase (microsomal) antibodies (TPOAs). Clinical presentation of diabetes, beta-cell autoimmune markers (GADAs and 1A2As), and evolution of insulin-secretory reserves and metabolic control during the first 2 years of follow-up were analyzed. Differences between groups were evaluated by Student's t test or the chi 2 test. The influence of TAI on follow-up data was evaluated by multiple logistic regression analysis. RESULTS: TAI was present in 31 patients (14 TPOA+ patients with normal thyroid function, 12 TPOA+ patients with thyroid dysfunction, and 5 patients with previously diagnosed TAI). TAI was more prevalent in women than in men (43.7 vs. 15.9%, P = 0.001). beta-Cell autoimmunity was more prevalent in patients with TAI than in those without TAI (93.5 vs. 76.3%, P = 0.03). The evolution of insulin requirements, metabolic control, and insulin-secretory reserves was comparable in the two groups. CONCLUSIONS: TAI is present in many type 1 diabetes patients at the time of diagnosis and is associated with a high prevalence of thyroid dysfunction. The clinical presentation of diabetes and the evolution of metabolic control and insulin-secretory reserves are not influenced by the presence of TAI. Patients with type 1 diabetes should be screened for TAI at diagnosis.