Thyroid ultrasound in diabetic patients without overt thyroid disease

Purpose: To assess thyroid volume and to evaluate possible lesions in the gland structure using thyroid ultrasound in patients with diabetes mellitus type 1 (DM1) and 2 (DM2) without overt thyroid disease. Material and Methods: Consecutive adult patients with DM2 (n=98) and DM1 (n=30) without overt thyroid disease referred to our department because of poorly controlled disease and/or diabetic complications were prospectively analyzed. Thyroid volumes, gland echogenicity, thyroid nodules incidence, and TSH levels were compared with control groups (n=50 and 38) and matched according to sex and age. Results: Significant increases in median thyroid volume were observed in both subjects with DM1 (17.3 cm(3), interquartile range ( IR) 13.9 - 21.6 cm(3) versus 14.4 cm(3), IR 11.3 - 18.3 cm(3); P<0.05) and DM2 (20.5 cm(3), IR 14.9 - 27.1 cm(3) versus 14.1 cm(3), IR 11.3 18.3 cm(3); P<0.001) in comparison to their control groups. Moreover, in the population of type 2 diabetics, thyroid nodules ( OR 2.37, 95% CI 1.14 - 4.93), parenchymatous goiter ( OR 5.40, 95% CI 1.20 - 24.30), and all kinds of thyroid goiter according to the WHO definition ( OR 4.18, 95% CI 2.02 - 8.66) were remarkably more frequent. In our patients, reduced ( but within normal range) TSH level occurred in DM1 ( median 0.97 mIU/l, IR 0.61 - 1.58 mIU/l versus median 1.66 mIU/l, IR 0.76 - 2.09 mIU/l; P<0.05). The presence of a negative linear correlation between thyroid volume and TSH concentration was noticed in patients with DM2 ( R-S=-0.38, P<0.01). Conclusion: In individuals with DM1 and DM2 treated for poorly controlled disease and/ or diabetic complications, thyroid volumes were significantly higher than in the normal population. Moreover, nodular thyroid structure and parenchymatous goiter occurred more frequently in these type 2 diabetic patients.