Prevalence of subclinical thyroid disorders in type 2 diabetes mellitus

Background: Subclinical thyroid disorders usually do not produce symptoms of thyroid disease until they turn into over thyroid disease. Thyroid disease is more common in people with diabetes mellitus than in the general population and it is important to detect thyroid disorder before its clinical manifestation. Subclinical hypothyroidism (SCH) can produce dyslipidemia, obesity thus resulting increased predisposition to coronary artery disease. Subclinical hyperthyroidism can aggravate hyperglycemia and impair blood sugar control. Objectives: Our objective is to determine the prevalence of subclinical thyroid disorders in patients with type 2 diabetes mellitus (T2DM) and to analyze the clinical and metabolic profile of patients with this dual endocrine disorder. Methods and Results: One hundred consecutive type 2 diabetic patients without clinical manifestations of thyroid disorders were screened for SCH and subclinical hyperthyroidism using serum free T3, free T4 and thyroid stimulating hormone (TSH) levels. Individuals of subclinical thyroid disease were further screened for thyroperoxidase (TPO) antibodies. SCH was detected in 13% of type 2 diabetic patients and none had subclinical hyperthyroidism in our study. SCH was common among females with type 2 diabetes (84.6%). Elevated TPO antibody levels were present in 84.6% SCH patients. Diabetic retinopathy among SCH patients showed significant association with higher serum TSH levels. Left ventricular diastolic dysfunction was present in 30.8% of SCH patients. Conclusion: SCH is common among type 2 diabetic patients, especially in females. It is most commonly secondary to autoimmune thyroid disease. Microvascular complications are commonly observed in this group of patients with dual endocrinal disorder and treating physician should be aware of the impact and should routinely screen SCH to prevent complications.