Autoimmune thyroid pathology in recently diagnosed diabetes mellitus type 1

OBJECTIVE: To analyze the prevalence of autoimmune thyroid disease among adult patients with recently diagnosed diabetes mellitus type I and its possible correlation with beta-cell autoimmunity markers (ICA, GAD, and IA 2) and with the presentation characteristics of diabetes mellitus. PATIENTS AND METHODS: A total of 100 patients diagnosed from 1992 to 1996 were included and anti-thyroid antibodies (Ac), anti-thyroglobulin (aTG) and antiperoxidase (aTPO) were measured. A comparison followed of the clinical characteristics, biochemical markers, and beta-cell immunity markers between the group of patients with positive and negative antibody determinations. Differences between groups were compared by the Student "t" test and non-parametric tests were used for cases not fulfilling the application conditions. RESULTS: Among the 100 patients, 25 had Ac+, two with previously known thyroid pathology and eight diagnosed at that moment. The group with Ac+ was characterized by a predominance of females (68% vs 32%; p = 0.001), lower bicarbonate levels (18.6 +/- 6.1 vs 21.3 +/- 6.4; p = 0.026) and higher requirements for insulin at discharge (0.77 +/- 0.22 vs 0.59 +/- 0.25 IU/kg; p = 0.002). Among patients in the Ac+ group, patients with thyroid pathology were characterized by a higher prevalence of females (90% vs 53.3%; p = 0.05) and a higher percentage of individuals with high anti-TPO titres (80% vs 33.3% higher than 400 IU/ml; p = 0.02). ICAs (66.6% vs 26.6% higher than 40 U JDF; p = 0.05) and IA2 (44.4% vs 0% higher than 12 IU/ml, p = 0.01). CONCLUSIONS: There is a high prevalence of thyroid pathology prevalence among our adult population with recently diagnosed DMI. Patients with thyroid autoimmunity have higher antibody titres to beta-cell and a somewhat more severe clinical presentation form. Prospective studies are required to determine the long term relevance of these differences.