Context: Thyroid hormone causes significant changes on the regulation of glucose homeostasis including IR [Insulin resistance]. There are no remarkable studies researching IR in geriatric and nongeriatric patients of Subclinical Hypothyroidism [SCH] and the changes observed with thyroxine treatment. Aims: To analyse Insulin resistance in newly detected SCH and Thyroxine supplemented cases of SCH and its comparison in elderly. Settings and Design: It was an observational cross-sectional hospital-based study. Methods and Material: It involved 120 SCH patients aged more than 18 years. Group A comprised 60 cases of newly diagnosed SCH cases and Group B was 60 SCH patients on thyroxine treatment for at least 3 months. For both the groups FBS, Fasting Insulin levels and HOMA IR [Homeostatic model assessment -estimated Insulin resistance] was calculated. Statistical analysis used: Inferential statistics was done using Mann Whitney U test and Pearson product moment correlation tests. Results: Group A consisted of 17 geriatric patients and group B had 19. Females made up 71% in group A and 83% in group B in both age groups. Comparison of Fasting Insulin levels and HOMA IR between A and B groups showed a significant difference (at 0.01 level). The duration of treatment had inverse correlation with HOMA IR with p=0.007 in non-geriatric population but not in geriatric population. Conclusions: Insulin resistance is present substantially in patients with newly detected SCH and decreases after administration of thyroxine in both geriatric and nongeriatric population. Keywords: BMI; Fasting Insulin levels; Geriatric; HOMA IR; Non-geriatric; Subclinical hypothyroidism;