Background-Diabetes mellitus (DM) is a common endocrine disorder. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are basic haematological indices to screen the coagulation status. Due to persistent hyperglycemia, glycation of proteins involved in clotting mechanism takes place which reduces their availability, thus affecting the clotting capacity. Method- An analytical observational study was conducted on 180 subjects by measuring their PT and aPTT, to observe the effect of antidiabetic drugs on blood coagulation and to compare these indices between treated and untreated diabetics. Results- A significant elevation of PT and aPTT in untreated diabetics when compared to controls was seen (PT (p<0.001); aPTT (p<0.05)). The effect of antidiabetic drugs showed normal mean values of PT and aPTT in treated group (p>0.05). Conclusion- the study revealed that significant elevation of PT and aPTT in untreated DM than non diabetic controls may be interpreted as tendency to bleed while effect of anti diabetic drugs shows normal mean values of PT and aPTT in treated group. This suggests that antidiabetic drugs either in combination or monotherapy may normalize PT and aPTT by reducing glycation of hemoglobin. Therefore, routine examinations of PT and aPTT are important to assess coagulation impairment in diabetes mellitus so as to prevent cardiovascular disease.