Background: Thyroid disease is considered frequent in the population. Regarding diabetes mellitus (DM), hypothyroidism and subclinical hypothyroidism are considered common, and risk factors for DM development. Objective: This work aimed to early prediction of diabetes mellitus among hypothyroidism patients and to correlate the serum FT3, FT4, and TSH with insulin resistance indexes and plasma insulin in cases with patients sub- and clinical hypothyroidism. Patients and methods: At the Endocrine out-patient clinic at the Internal Medicine Department, Faculty of Medicine, Zagazig University Hospitals a total of 162 adult participants, 54 cases of overt hypothyroidism, and 54 patients with subclinical hypothyroidism (SCH) were studied in this case-control study. The cases were aliquoted into three groups: Group (A): 54subjects euthyroid (control), Group (B): 54 cases with SCH, and Group (C): 54 cases with Overt hypothyroidism. Results: The results showed that FT3 was significantly negatively correlated with cholesterol, HDL, FBG, and HbA1C. FT4 was significantly negatively correlated with TPO antibody and HbA1C but significantly positively correlated with cholesterol. TSH was significantly negatively correlated with TAG but significantly positively correlated with TPO antibody and regard FBG, F.INS and HOMA_IR were significantly high among sub- and clinical hypothyroidism groups than the control group. Conclusion: The current study concluded a significant correlation between thyroid hormones and IR (HOMA-IR). The evaluation of IR is crucial in clinical events, and for the settlement of insulin sensitivity. To predict type2 DM in hypothyroid patients.