Introduction: Glycated hemoglobin (HbA1c) has been considered as an important marker of long term glycemic control. A value between 5.7% and 6.5% represents prediabetes while a value 6.5% is considered as diabetes mellitus. Conditions which are associated with a low RBC turnover, with a predominance of older cells in circulation are associated with a falsely elevated HbA1c in which hypothyroidism is an important and common etiological factor. We designed this study to determine the effects of thyroid dysfunction on HbA1C level in non diabetic subjects. Material and method: HbA1c level and reticulocyte count were measured in 100 non diabetic subjects those were newly diagnosed hypothyroidism and hyperthyroidism (Group I) and who were already diagnosed hypo and hyperthyroidism in euthyroid state after treatment (Group II). We compared HbA1C and RC between group I and group II. Results: HbA1C level significantly high in newly diagnosed hypothyroidism in comparison to treated hypothyroid patients (5.95±0.57 vs 5.34 ± 0.45, P value =0.0001) and among hyperthyroid patients HbA1C level (5.34±0.36 vs 5.2 ± 0.39 , P value= 0.2176) which was not significant (>0.05). A positive Correlation between the levels of TSH and HbA1C in hypothyroid patient by Pearson’s correlation coefficient. Reticulocyte count also significantly low in newly diagnosed hypothyroidism patients(1.14 ±0.43 vs 1.54 ± 0.38 P value=0.0012).Correlation between the levels of Reticulocyte count and HbA1C in Group I by Pearson’s correlation coefficient is negative{r = –0.3585, p < 0.0001 (S)} which means there is a tendency for high HbA1C scores to go with low RC scores. Conclusion: HbA1C levels was significantly higher among hypothyroidism patients which was in pre–diabetic range despite normal blood sugar levels. Significant difference not observed in hyperthyroid patient.