Role of microRNAs in regulation of insulin secretion and insulin signaling involved in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder due to insulin resistance that can be caused by both genetic and environmental factors. In 2018, the American Diabetes Association (ADA) estimated more than 500 million T2DM cases globally. In recent years, studies conducted on humans and animals have suggested that non-coding RNAs, namely, microRNAs (miRNAs), post-transcriptionally regulate gene expression that can bring changes in normal physiology, resulting in the development of metabolic diseases. miRNAs also regulate different cellular processes including insulin synthesis and its secretion from pancreatic beta-islet cells, its development and function, insulin signaling and glucose homeostasis. Dysregulation of miRNA can affect the functioning of different tissues during the progression of T2DM. This review focuses on various miRNAs that influence the development of beta-cells and insulin secretion, various protein cascades that play an important role in insulin signaling and glucose uptake, and their role in insulin resistance. Similarly, the long noncoding RNAs also known as lncRNAs and their beta-cell characteristics involved in T2DM have been discussed. Finally, the significance of miRNAs and their mRNA targets as effective biomarkers and therapeutics in studying the early onset and progression of T2DM have been highlighted.