Association between altered thyroid state and insulin resistance

To determine the association between altered thyroid hormones and insulin resistance (IR).

Eight euthyroid (EU), eight hypothyroid (HO), and eight hyperthyroid (HR) patients with no past medical history were studied in this cross-sectional study at the Care Institute of Medical Sciences, Ahmedabad, India, The fasting blood sample were analyzed for thyroid stimulating hormone (TSH), lipid profile, insulin, and glucose. Homeostatic model assessment (HOMA) was calculated for assessing IR.

HOMA values were significantly higher in HR and HO groups as compared to the EU group (P < 0.05). Insulin levels were also found to be significantly increased in HR and HO groups as compared to the EU group (P < 0.05). Cholesterol, triglycerides (TG), and low density lipoprotein (LDL) were significantly raised in HO as compared to EU and HR groups (P < 0.05) whereas high density lipoprotein levels (HDL) were lower. HOMA and insulin were found to be positively correlated with TSH in HO and negatively in HR.

Thyroid disorder, including both hypo- and hyper have been associated with IR due to various mechanisms such as altered insulin secretion and lipid levels. IR was comparable in patients with both HO and HR. Although HO and HR constitute an IR state, more studies need to be done in order to clarify the underlying pathogenic mechanism. Thus, an altered thyroid state can lead to IR leading to glucose-related disorder such as diabetes dyslipidemia.