THYROID AND GLUTEN METABOLISM: INTERACTIONS BETWEEN THYROID DYSFUNCTION AND DIABETES MELLITUS

Abstract

Introduction: The complex interrelationship between thyroid hormones and glucose homeostasis has proven to be a critical point in clinical endocrinology, since both pathologies frequently coexist and mutually influence each other. T3 and T4 hormones exert pleiotropic effects on carbohydrate metabolism, acting from intestinal glucose absorption to modulation of insulin sensitivity in peripheral tissues and regulation of hepatic gluconeogenesis. In hyperthyroidism, an acceleration of glycemic turnover and potentiation of insulin resistance were observed, while hypothyroidism was associated with a reduction in insulin clearance rate and a higher risk of metabolic disorders. Objective: The objective of this systematic review was to analyze the scientific evidence regarding these pathophysiological interactions. Methodology: The research followed the PRISMA checklist guidelines, with searches conducted in the PubMed, SciELO, and Web of Science databases. The following descriptors were used: thyroid dysfunction, diabetes mellitus, glucose metabolism, insulin resistance, and autoimmunity. The selection encompassed articles published in the last decade. Inclusion criteria included original studies, clinical trials, and systematic reviews addressing hormonal correlation. Exclusion criteria were studies with animal samples, isolated case reports, and articles with incomplete methodology. Results: The results demonstrated that the prevalence of thyroid diseases was significantly higher in diabetic patients, especially in type 1, due to the shared autoimmune etiology. It was noted that the thyrotoxic state worsened glycemic control by increasing hepatic glucose production, while hormone replacement in hypothyroidism improved insulin sensitivity in patients with metabolic syndrome. Conclusion: It was concluded that systematic screening of thyroid function in patients with diabetes has become essential for therapeutic optimization, given the profound mutual influence between these endocrine axes in maintaining systemic metabolic balance.