Subclinical Hypothyroidism- An Undermined Aetiology for Uncontrolled Diabetes Mellitus Type II

Abstract

BACKGROUND Type 2 diabetes and thyroid disorders are the two most common endocrinopathies. 1 Several studies have demonstrated relationship between DM type 2 and thyroid dysfunction, but there are only a few studies done to evaluate the association between subclinical hypothyroidism and glycaemic control of the diabetic patients. METHODS It was a cross sectional case control study in 100 diabetic patients out of which 50 cases had poor glycaemic control and 50 controls were patients with good glycaemic control. Subclinical hypothyroidism was defined as elevated TSH (>4 mIU/L) with normal free T4 and in absence of any clinical features. RESULTS 50 age and sex matched diabetics with HbA1c >6.5 were compared with diabetics with HbA1c <6.5 for thyroid abnormalities. 15% uncontrolled diabetic male and 30% of uncontrolled females had subclinical hypothyroidism compared to 0% male and 11% female with HbA1c <6.5. This when compared to hypothyroid frequency among case and control groups was found to be 5% males and 3.3% females compared to 0% and 3.7% in control group respectively. The frequency of hyperthyroidism was 5% and 6.7% in male and females of case group compared to 4.3% and 3.7% in male and female of control group. CONCLUSIONS The prevalence of subclinical hypothyroidism was more in the group with poor glycaemic control as compared to patients with HbA1c <6.5. Diabetics with poor control have an underlying subclinical hypothyroidism which may accentuate impaired glycaemic control and vice versa.