The pathogenesis of type 2 diabetes mellitus (T2DM) is based on the development of insulin resistance, which is a disruption to the ability of the tissues to bind to insulin, leading to a general metabolic disorder. Mitochondria are the main participants in cellular energy metabolism, meaning their dysfunction is associated with the development of insulin resistance in T2DM. Mitochondrial function is affected by insulin resistance in various tissues, including skeletal muscle and the liver, which greatly influence glucose homeostasis throughout the body. This review studies mitochondrial dysfunction in T2DM and its impact on disease progression. In addition, it considers the causes underlying the development of mitochondrial dysfunction in T2DM, including mutations in the mitochondrial genome, mitochondrial DNA methylation, and other epigenetic influences, as well as the impact of impaired mitochondrial membrane potential. New therapeutic strategies for diabetes that have been developed to target the mitochondria will also be presented.