Endocrine Abstracts

Introduction: The association of type 1 diabetes mellitus (DM1) with thyroid diseases is well known, especially in the field of polyglandular autoimmune diseases. Thyroid status can influence the necessary of insulin – decreased in hypothyroidism and higher in hyperthyroidism. We wanted to evaluate the prevalence of thyroid pathology in patient with DM1.

Patients and methods: Cross-sectional study including 66 patients with DM1 (23 men, 43 women) aged between 20 and 65 years and 50 healthy volunteers age and sex matched (group B), evaluated biologically (TSH, fT₄, anti-thyroidperoxidase antibody – TPO) and morphologically (thyroid ultrasonography).

Results: Autoimmune thyroiditis (AIT) was significantly more frequent in DM1 group (56 vs 16%, P=0.006), as well as thyroid hypoechogenicity (48.5 vs 26%, P=0.017). We found a good correlation between thyroid hypoechogenicity and autoimmunity (r²=0.417, P=0.006). Hypothyroidism was confirmed in 12 cases (18.2%; 9 overt and 3 subclinical), more frequent in those with AIT (27 vs 6.9%, P=0.001), and in only 3 cases (6%) in control group. None of our subjects had hyperthyroidism.

Discussion: Thyroid autoimmunity and dysfunctions are more frequent in DM1 patients than in general population. Hypothyroidism is associated with diminished insulin necessary, with higher requirement once TSH normalised, which impose rigorous glycaemic control. Owing to the good correlation between thyroid hypoechogenicity and ATPO levels, thyroid us may be a useful tool in assessment thyroid status.

Conclusion: Screening of thyroid diseases should be systematic in DM1 patients in order to detect unknown thyroid dysfunctions.