Diabetes and thyroid diseases - a review

Abstract

The fact that insulin and thyroid hormones influence each other actions assumes significance since diabetes mellitus and thyroid disease are the two common endocrine disorders in adult population. Poorly controlled diabetes results in a low T3 state and a loss of TSH response to TRH. Regardless of glycemic control there is an absence of nocturnal THS peak. There is an increased incidence of dysthyroid optic neuropathy in patients with Graves disease and coexistent diabetes. Also, the visual prognosis after treatment is poor. 50% of thyrotoxic patients who were previously euglycemic exhibit variable glucose intolerance while frank diabetes occurs in 2-3% cases. In diabetic patients presence of thyrotoxicosis deteriorates the glycemic control. Diabetic patients with hypothyroidism may suffer from recurrent episodes of hypoglycemia. Type 1 diabetes mellitus patients have a high prevalence of thyroid dysfunction with nearly one third of all newly detected patients showing thyroid autoimmunity. Also, Type 1 diabetes mellitus and hypothyroidism co-exist in downs syndrome as well as congenital rubella. In autoimmune polyglandular syndrome Type 2, autoimmune thyroid disease and immune mediated diabetes are among the components.