Elite Journal of Laboratory Medicine. Volume 2 issue 3(2024), Pp. 11-28 https://epjournals.com/journals/EJLM Citation: Ogbu ISI, Ejike-Odeh EJ, Obeagu EI. Insulin Resistance: A Review. Elite Journal of Laboratory Medicine, 2024; 2(3): 11-28 1 Insulin Resistance: A Review Ogbu, I.S.I 1 , Ejike-Odeh, Ezinne Jane 1 and Emmanuel Ifeanyi Obeagu 2 1 Department of Medical Laboratory Science, Evangel University. Akaeze. Ebonyi State, Nigeria. 2 Department of Medical Laboratory Science, Kampala International University, Uganda. Abstract Insulin is a peptide hormone produced by the islet cells of the pancreas that has multifarious effects on body metabolism. Insulin resistance is a prevalent medical condition that accompanies type 2 diabetes, obesity, hypertension, metabolic syndrome and polycystic ovarian disease. It is a state in which higher than normal concentrations of insulin are needed for normal responses, leading directly to hyperinsulinaemia and impairment in some of its action. Its pathogenesis is yet not fully understood and that has restricted the treatment of type 2 diabetes and associated conditions. This review examines insulin resistance from the mode of action of insulin to its causes and consequences highlighting the recent findings with a view to making the condition better understood. Literature search was conducted from 1973 to date and 250 publications were reviewed. The mechanism of action of insulin is important in the understanding of insulin resistance. Changes in the downstream events following insulin- receptor interaction may play significant roles in the pathogenesis of insulin resistance. Currently, the roles of counter-action hormones including adipokines are fairly understood. More research is needed in the downstream events of insulin- receptor interaction to elucidate the pathogenesis of insulin resistance. This will change the current perception and practice in the treatment of type 2 diabetes and metabolic syndrome. Keywords. Insulin resistence (IR); hyperinsulinaemia, obesity, type 2 diabetes, impaired glucose tolerance, IR Index; hormone action. Introduction Insulin resistance (IR) is a common medical issue that goes hand-in-hand with polycystic ovarian disease (PCOD), type 2 diabetes (T2D), obesity, hypertension, and metabolic syndrome (MetS) (1-2). Despite playing a significant role in the etiology of T2D and the metabolic syndrome, the processes behind IR are still poorly understood. It is a complicated metabolic condition with a pathogenesis that is interwoven. The insufficient knowledge of IR has limited the therapy of T2D. A deeper comprehension of IR processes is necessary to change diabetes from a deadly diagnosis to a chronic condition that can be treated medically. New pharmaceutical targets for the treatment of the metabolic syndrome and T2D will become apparent as a result of better understanding of the molecular/biochemical abnormalities responsible for IR. This review examines the IR phenomena with the aim to highlight aspects of IR needing attention for better understanding which will facilitate the management T2D.