Thyroid ultrasound in diabetic patients without overt thyroid disease

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.

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.

Significant increases in median thyroid volume were observed in both subjects with DM1 (17.3 cm3, interquartile range (IR) 13.9-21.6 cm3 versus 14.4 cm3, IR 11.3-18.3 cm3; P < 0.05) and DM2 (20.5 cm3, IR 14.9-27.1 cm3 versus 14.1 cm3, IR 11.3-18.3 cm3; 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 (RS = -0.38, P < 0.01).

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.