Reduced insulin sensitivity in differentiated thyroid cancer patients with suppressed TSH

Objective: TSH-suppression is a therapy for thyroid cancer management, but it may lead to adverse effects, which should be balanced with its benefits. Previous studies evaluating the consequences of TSH suppression on insulin sensitivity have only been done with indirect techniques, and results were controversial. Therefore, we aimed to assess insulin sensitivity in patients with thyroid cancer and suppressed thyroid-stimulating hormone (TSH) with the most appropriate direct method (hyperinsulinemic-euglycemic clamp) in order to get a more conclusive response about the topic. Methods: A group of 20 non-obese and non-diabetic thyroid cancer patients with suppressed TSH underwent a hyperinsulinemic-euglycemic clamp to evaluate insulin sensitivity. Their results were compared to the results of a sex and body mass index (BMI) -paired control group composed of 20 healthy volunteers. Results: Patients were all female, aged 36.8 +/- 10.2 years-old, with mean TSH 0.1 +/- 0.1 IU/mL and mean BMI 26.2 +/- 3.3 kg/m(2). Insulin sensitivity, determined by the insulin-stimulated glucose uptake (M-value), was lower in the patients group (4.2 +/- 1.6mg/min*kg versus 5.8 +/- 1.7, age-adjusted p-value = 0.0205). Conclusion: This study shows for the first time that subclinical thyrotoxicosis in patients with thyroid cancer is associated with insulin resistance, as measured by hyperinsulinemic-euglycemic clamp technique. Such finding may be taken into consideration by clinicians when balancing risks and benefits of TSH-suppression therapy in thyroid cancer patients.