Background: Diabetes mellitus (DM) is a group of aetiologically different metabolic disorder characterized by hyperglycemia due to inadequate insulin secretion or defect in insulin action or both. There is strong correlation between DM and thyroid hormones. Objective: The aim of this study was to find out the association between hypothyroidism and type 2 diabetes mellitus in north Indian patients to evaluate the hyperglycemic effect by correlating fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c) and thyroid profile parameters. Methods: 50 type-2 DM patients and 50 controls were studied for their thyroid profile along with their fasting glucose levels and glycosylated hemoglobin (HbA1c). Analysis was performed by comparing the values with age and matched controls using student‘t’ test. Results: Analysis showed that in type 2 diabetes mellitus patients and thyroid dysfunction prevalence rate in our study is high. Serum tri-idothyronine (T3) and tetra-idothyronine (T4) hormone concentrations were low and Thyroid Stimulating Hormone (TSH) concentrations were high in Type 2 DM when compared to controls. The T3 (p value <0.05), T4 and TSH (p value: <0.001) shows significant difference. FSG (p value: <0.05) also show significant correlations with thyroid profile parameters. Type 2 Diabetes Mellitus patients are at risk for hypothyroidism and hence have to be followed up with serum TSH levels. There was significant and inverse relation of HbA1c with thyroid hormone level whereas level of serum TSH was seen to have significant and direct relation with HbA1c.
Conclusion: Insulin an anabolic hormone metabolizes glucose enhances the level of freeT4 (FT4) while it suppresses the level of T3 by inhibiting hepatic conversion of T4 to T3. On the other hand some of the oral hypoglycemic agents such as the phenylthioureas are known to suppress the level of FT4 and T4, while causing raised levels of TSH
Keywords: Diabetes mellitus; TSH; T4; T3