Thyroid Dysfunction and Diabetes Mellitus: A Complex Interdependent Interaction

Thyroid diseases and diabetes mellitus are, arguably, among the commonest endocrine disorders worldwide. Diabetes mellitus (DM), a common endocrine metabolic disorder, is an important cause of morbidity and mortality worldwide. Thyroid dysfunction has been frequently encountered in diabetic patients with hypothyroidism being the most common type of dysfunction. Diabetics have a higher prevalence of thyroid disorders when compared with the general population. Alteration in thyroid function complicates the management of diabetes mellitus and its complications. Thyroid hormones contribute to the regulation of carbohydrate metabolism and pancreatic function, and on the other hand, diabetes affects thyroid function tests to variable extents. This chapter demonstrates the importance of recognizing this interdependent relationship between thyroid disease and diabetes, which will help its early diagnosis and treatment and guide clinicians on the optimal screening and management of these conditions.