Mathematical model of evaluation of Insulin Resistance using Homeostasis Model Assessment – Insulin Resistance Index in patients with Hyperthyroidism

Aim: To evaluate insulin resistance using HOMA-IR index in patients with overt and subclinical hyperthyroidism. Materials and Method: A randomized case control study on female population was conducted. For which 30 overt hyperthyroid, 30 subclinical hyperthyroid and 30 age and sex matched Euthyroid controls were selected. Biochemical parameters like Total triiodothyronine (T3), Total Thyroxine (T4), Thyroid Stimulating Hormone (TSH), Fasting Insulin, Fasting Blood glucose were estimated from serum samples in auto analyzers. HOMA-IR Index was calculated using formula [Fasting insulin in uIU/ml × Fasting blood glucose in mg/DL / 405]. Statistical analysis was done using Graph pad prism software, parameters expressed in Mean ± SD, individual changes was assessed by students “t” test and Pearson's coefficient of correlation was used. Results: HOMA-IR was significantly high in cases than control group (p<0.0001), Insulin levels were also high in cases compared to controls (p<0.0001). HOMA-IR index and Insulin levels were negatively correlated with TSH, in both overt and subclinical hyperthyroid cases than controls (r=0.97, p=0.0001 and r=0.45, p=0.001 respectively). Conclusion: Insulin resistance which was calculated by HOMA-IR index indicates the presence of insulin resistance in both overt and subclinical hyperthyroidism.