The goal of this clinical trial to clarify the impact of changes in thyroid hormone levels on glucose and lipid metabolism. Patients will be included in whom thyroid hormone levels are intentionally changed by treatment. In patients with Graves' disease, thyroid hormone levels will be lowered using medication, while in patients with thyroid cancer, thyroid hormone levels will be raised using medication. Oral glucose tolerance tests will be performed before treatment and at two time points after treatment begins to assess metabolic effects.
This research project aims to clarify the role of changes in thyroid hormone levels in glucose and liver metabolism. Thyroid hormones regulate endogenous glucose production, insulin sensitivity, lipid metabolism, and lipid storage in the liver. They also appear to enhance insulin sensitivity in other tissues. Furthermore, thyroid hormones stimulate lipolysis and reduce total and LDL-cholesterol levels. The impact of thyroid hormones on insulin secretion is controversial, with some trials demonstrating increased secretion and others showing decreased secretion. Most of this evidence is derived from animal trials, and prospective human trials are lacking. Clinical scenarios where thyroid hormone levels are altered through therapeutic interventions will be used. In patients with Graves' disease, hyperthyroidism is pharmacologically reduced, whereas in patients with thyroid carcinoma, hyperthyroidism is pharmacologically induced. Before the start of treatment, two weeks and three months after start of treatment oral glucose tolerance tests will be performed for metabolic characterization. Using this approach, differences in glycemic, insulin sensitivity, insulin secretion, lipids, resting energy expenditure, respiratory quotient, hepatic steatosis, eating and exercise behavior will be assessed.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
60
Participants will receive a 75 g oral glucose tolerance (3h) before the start of treatment, two weeks and three months after start of treatment. Body composition will measured by bioimpedance analysis. Before and during the oral glucose tolerance test, indirect calometry will assess metabolic flexibility.
Ulm University Hospital
Ulm, Baden-Wurttemberg, Germany
RECRUITINGInsulin sensitivity
Effect of changes in thyroid hormone levels on whole-body insulin sensitivity, assessed from glucose and insulin measurements during the 75 g oral glucose tolerance test.
Time frame: Baseline, 2 weeks, 3 months
Insulin secretion
Effect of changes in thyroid hormone levels on insulin secretion, assessed from glucose and insulin/c-peptide measurements during the 75 g oral glucose tolerance test.
Time frame: Baseline, 2 weeks, 3 months
Resting energy expenditure.
Effect of changes in thyroid hormone levels on resting energy expenditure assessed by indirect calometry before and during the 75 g oral glucose tolerance test.
Time frame: Baseline, 2 weeks, 3 months
Respiratory Quotient
Effect of changes in thyroid hormone levels on respiratory quotient assessed by indirect calometry before and during the 75 g oral glucose tolerance test.
Time frame: Baseline, 2 weeks, 3 months
Lipid metabolism
Effect of changes in thyroid hormone levels on lipid metabolism assessed from lipid measurements during the 75 g oral glucose tolerance test.
Time frame: Baseline, 2 weeks, 3 months
Hepatic steatosis
Presence of hepatic steatosis assessed by liver ultrasound including elastography.
Time frame: baseline
Heart rate variability
Effect of changes in thyroid hormone levels on heart rate variability assessed by electrocardiography during the 75 g oral glucose tolerance test.
Time frame: Baseline, 2 weeks, 3 months
Eating behavior
Effect of changes in thyroid hormone levels on eating behavior assessed by dietary protocols before the start of treatment and 3 months later.
Time frame: Baseline, 3 months
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