Endocrine Abstracts

Background

Thyroid diseases and diabetes are the two most common endocrinopathies. A relationship between these two conditions is suggested by many studies, as diabetic population seems to present increased thyroid impairment. However, clinical data are still very sparse.

Aim

To evaluate thyroid morphologic characteristics among patients with different glucose tolerance status.

Material and methods

This retrospective study was conducted on 227 patients who underwent both an oral glucose tolerance test (OGTT) and an thyroid ultrasound (US) exam at our center. The following data were collected: thyroid US characteristics, thyroid nodules cytology, glucose tolerance defined as normal (N), impaired (I) and type 2 diabetes (D). HOMA index was also calculated.

Results

The cohort included 44 males and 183 females. After OGTT, 58%, 34% and 7% of patients were identified as (N), (I) and (D), respectively. (D) were significantly older (67.4 ± 6.8 yr) as compared to (I) (56.9 ± 13.5 yr) and (N) (52.3 ± 16.5 yr), without differences concerning thyroid function and gender distribution. (D) presented higher mean thyroid volume than others, but this difference did not reach statistical significance. Thyroid volume was significantly higher in euthyroid patients as compared to hypothyroid patients on L-thyroxine replacement therapy. Mean insulin peak levels after glucose load was consistently higher in (D). The incremental area under the curve (AUCins) increased from (N) to (I) to (D). Simple linear regression did not show any correlation between thyroid volume and insulin level nor HOMA index. Thyroid nodules were diagnosed in 68% of (N), 64% of (I) and 82% of (N). Thyroid nodules presented US characteristics suspicious for malignancy in (D) more often than other groups. 174 out of 203 nodules underwent to cytology investigation. Benign cytology was prevalent in all three groups.

Conclusion

Our data suggest a correlation between impaired glucose tolerance and increased thyroid volume, in agreement with literature evidence. More prospective studies with larger samples are needed in order to confirm this association. Finally, impaired glucose tolerance was not found to be predictive of malignancy at US and cytology.