Diabetes mellitus (DM), most common endocrine disorder, characterized by persistent hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Development of diabetes involves several pathogenic processes ranging from autoimmune destruction of the β cells of the pancreas with consequent insulin deficiency to abnormalities that result in resistance to insulin action [1]. Hyperglycemia is the principal cause of diabetic complications. Sedentary lifestyle, various diet patterns, ethnicity, and genetic predisposition are the major factors responsible for the causes of the epidemic [2]. Thyroid disorders are also common in the general population and it is the second most common endocrine disorder. As a result, it is common for an individual to be affected by both thyroid disease and diabetes [3]. Various studies have reported the low prevalence of thyroid dysfunction among diabetic patients, between 2.2 to 17 % in their respective populations [4,5]. However, few studies have shown a higher prevalence of thyroid dysfunction in diabetes from 31 % to 46.5% [6,7]. Thyroid hormones and insulin are the antagonists and both are involved in cellular metabolism of carbohydrates, proteins, and lipids. The functional impairment occurs in thyroid hormone as well as insulin if their levels changed [8]. DM appears to influence thyroid function in two sites; firstly, at the level of hypothalamic control of TSH release and secondly at the conversion of T4 to T3 in the peripheral tissues. Hyperglycemia causes reversible reduction of the activity and hepatic concentration of T4 5’deiodinase, low serum T3, increase in reverse T3 and also variation in the level of T4 [9]. The recognition of this interdependent relationship between thyroid disease and diabetes is of importance to guide clinicians on the optimal management of both these conditions. With this, the study was planned to find the prevalence of thyroid dysfunction in type 2 DM.

Settings: Study was conducted in the department of General Medicine, GSL Medical College.

Duration of study: The study was conducted from November 2015 to April 2017.

Sampling method: Random sampling was considered in this study.

Inclusion criteria: All type 2 diabetics aged >30

hypothyroidism in type 2 diabetics. Age-wise, in euthyroid category, 4.8% (5) were in 30-40 years group, 27% (28) in 41-50 years group, 28.8% (30) in 51-60 years group, 20% (21) in 61-70 years group and 1.9% (2) in >71 years group. In the subclinical category, 1.9% (2) were in the 30-40 years group, 4.8% (5) in 41-50 years group, 3.8% (4) in 51-60 years group, 1.9% (2) in 61-70 years group. In the clinical category, 9% (1) in the 41-50 years group, 1.9% (2) in the 51-60 years group, 1.9% (2) in 61-70 years group. Statistically, there was no significant difference (Table 1).

Table-1: Age-wise thyroid function results among type 2 diabetics; n (%).

Gender wise, in males, 32.6% (34) were euthyroid, 5.8% (6) were subclinical and 1.9% (2) were clinical. In the female, 50% (52) were euthyroid, 6.7% (7) were subclinical and 2.9% (3) were clinical. Statistically, there was no significant difference (Table 2).

Table-2: Gender wise thyroid function results among type 2 diabetics; n (%).

When thyroid test results were correlated with dyslipidemia, in euthyroid, 32% DM had dyslipidemia; Dyslipidemia was resent in 12.5% and 4.8% cases respectively in subclinical and clinical cases. Whereas in 51% of cases dyslipidemia was not identified. Statistically, there was a significant difference (Table 3).

Table-3: Thyroid function results among type 2 diabetics with dyslipidemia; n (%).

incidence of thyroid disorder among females; 36%, 22%, respectively and elder population with > 60 years, had more incidence of thyroid disorder [14]. Epidemiological studies reported 2-4%, 4-20% of overt hypothyroidism and subclinical hypothyroidism range respectively and higher incidence among women with > 60 years age [15,16]. Hypothyroidism or thyroid overactivity is most frequently induced by an autoimmune process. It was mentioned that the number of people with thyroid disorders in India exceeds 40 million [17]. Various studies in the recent past have revealed a higher incidence of thyroid dysfunction in diabetics compared to the normal population. In population studies, overt hypothyroidism or its subclinical manifestations range between 2-4% and 4-20% respectively both being significantly higher in women above the age of 60 years [16]. Hypothyroidism is a clinical state due to the decreased secretion of thyroid hormones viz., thyroxine and triiodothyronine or very rarely due to the decreased activity of these hormones at tissue levels. The term ‘subclinical hypothyroidism’ is used to define that grade of primary hypothyroidism in which there is an elevated thyroid-stimulating hormone concentration in the presence of normal serum free thyroxine and triiodothyronine concentrations. Subclinical hypothyroidism may progress to overt hypothyroidism in approximately 2-5% cases annually. All patients with overt hypothyroidism and subclinical hypothyroidism with TSH > 10mIU/L should be treated [18]. Hyperthyroidism leads to lipid peroxidation whereas hypothyroidism causes diminished glucose oxidation. LDL clearance leads to lowered cholesterol and triglyceride levels. It has been reported that T3 enhances fasting plasma glucose and free fatty acid levels [19]. In the present study, dyslipidemia was identified in 32%, 12.5%, 4.8% participants, respectively in euthyroid, subclinical and clinical hypothyroid patients, statistically, the difference was significant (Table 3; P<0.05). Literature also reported a high percentage of severe clinical hypothyroidism (SCH) [20]. These changes might indicate that elevated TSH can affect blood lipids and vascular endothelium in patients with Type 2 diabetes, although whether SCH is the primary reason for the high prevalence of CHD remains controversial. Whereas dyslipidemia was reported to be 95.5% among the type 2 DM in one cross-sectional report [21,22,23].