Oxidative Stress in Type 2 Diabetes Mellitus – A Key Factor for Major Complications Darshana Kottahachchi a * , Erandie Perera b , Ridmi Maddumage b , Mohammad Azam Mansoor c a darsha.uda@gmail.com a Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, General Sir John Kotelawala Defence University, Ratmalana (10380), Sri Lanka. b Department of Basic Sciences, Faculty of Allied Health Sciences, General Sir John Kotelawala Defence University, Ratmalana (10380), Sri Lanka. c Department of Natural Sciences, Faculty of Engineering and science, University of Agder, Kristiansand (4611), Norway. Abstract Diabetic Mellitus (DM) is considered as a metabolic disorder resulting from flaws in the secretion of insulin, action of insulin or both together. The international diabetes federation reported that approximately 5.0 million deaths were assigned to diabetes mellitus in 2017 and it accounted for 9.9% of all causes of mortality among people globally. It has been reported that 1 in 11 adults, approximately 463 million people have diabetes mellitus worldwide. In Sri Lanka, 1 in 5 adults has either diabetes or pre-diabetes and one third of those with diabetes are undiagnosed. Type 2 DM which is characterized by hyperglycemia is the most frequent type of diabetes, accounting for around 90% of all diabetic cases. Recent clinical findings explore that the underlying pathways in the pathogenesis of diabetic complications are mainly due to oxidative stress generated by over production of reactive oxygen species (ROS) during hyperglycemia. Therefore, diabetes mellitus is recognized as a redox disease. Uncontrolled hyperglycemia causes tissue damage through several biochemical mechanisms thereby leading to a variety of diabetic associated complications including nephropathy, neuropathy, peripheral vascular diseases, and retinopathy. In this review, we focus on possible mechanisms of tissue damage due to oxidative stress in type 2 DM patients during hyperglycemia. Furthermore, we discuss some of the major complications of post type 2 DM such as cardiovascular disease (CVD) and nephropathy. Thereby, in this review an attempt has been made to sum up the available literature regarding post diabetic complications and possible mechanisms enabling the researchers to conduct innovative research in this area. Keywords: Diabetes Mellitus; Oxidative stress; ROS; Hyperglycemia, Tissue damage 66 www.ijrp.org IJRP 2021, 70(1), 66-71; doi:.10.47119/IJRP100701220211740