American Diabetes Association has suggested the use of HbA1c as diagnostic tool for prediabetes and diabetes. A value between 5.7% and 6.5% represents prediabetes while a value ≥6.5% is considered as diabetes mellitus. However several factors other than glycemic status can influence HbA1c levels factors which affect the RBC turnover like Haemoglobinopathies (sickle cell anemia etc.) even Blood transfusion and as Thyroid status affects cell turnover it is being hypothesised that thyroid status changes( hypo or hyperthyroid) will cause raised levels of HB1AC levels. Raised HB1AC levels in thyroid disorders can falsely classify patients as prediabetic. The aim of the study was to determine the effects of altered thyroid status on HbA1c levels in individuals without diabetes with overt hyper- and hypo-thyroidism. All newly diagnosed cases matching the inclusion criteria(attending the outdoors of medicine department DMCH Laheriasarai) with thyroid disorders between 1st april 2017 till 31st october 2018 in Department of Medicine DMCH were included in the study with equal numbers of age and sex matched controls. Results showed an increased level of HBA1C in patients with thyroid disorders and the presumed conclusion was that in patients with thyroid disorders glycated haemoglobin is not an assured marker of imapired glucose metabolism and other methods should be used.