Thyroid function is central in the control of physiological and pathophysiological processes. Studies in animal models and human research have determined that
thyroid hormones modulate cellular processes relevant for aging and for the majority of age-related diseases. While several studies have associated mild reductions on
thyroid hormone function with exceptional longevity in animals and humans, alterations in
thyroid hormones are serious medical conditions associated with unhealthy aging and premature death. Moreover, both
hyperthyroidism and
hypothyroidism have been associated with the development of certain types of diabetes and
cancers, indicating a great complexity of the molecular mechanisms controlled by
thyroid hormones. In this review, we describe the latest findings in
thyroid hormone research in the field of aging, diabetes, and
cancer, with a special focus on
hepatocellular carcinomas. While aging studies indicate that the direct modulation of
thyroid hormones is not a viable strategy to promote healthy aging or longevity and the development of thyromimetics is challenging due to inefficacy and potential toxicity, we argue that interventions based on the use of modulators of
thyroid hormone function might provide therapeutic benefit in certain types of diabetes and
cancers.