Gut Microbiota and Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is characterized by poor insulin secretion from pancreatic beta cells together with reduced insulin sensitivity of adipose tissue, liver, and muscle. This results in an improper response to fasting and refeeding, and hyperglycemia causing acute and chronic complications associated with T2DM. The International Diabetes Federation estimates that there are 537 million adults aged 20–79 with diabetes in 2021 and this number is projected to rise to 643 million by 2030. The incidence of T2DM is largely driven by obesity pandemic and is increasing at alarming rates. In the development and progression of T2DM, the primary role of environmental factors such as smoking, poor diet, and sedentary lifestyle is well known. Genetic susceptibility has also been studied, and many genes that determine the hormonal regulation of glucose and lipid metabolism have been found to be associated with T2DM. The human gut microbiota can be considered an organ with important functions for human metabolism, digestion, maintenance of the intestinal barrier function, and immunomodulation. It helps to modulate host metabolism and its change appears to be related to the development of T2DM and cardiometabolic disorders associated with overweight and obesity.