Diabetes is one of the biggest health problems in the world, and has quite high incidences of disability and mortality, which increase the cost of health care to countries and financial burden on patients. In the past decade, many studies have shown that there is an association between changes in the intestinal flora and various systemic diseases, including diabetes. It is well known that factors such as lifestyle, increased intake of fat and high-sugar foods, and host genes may all contribute to type 2 diabetes mellitus (T2DM). Some recent studies have shown that changes in the composition of intestinal flora can trigger T2DM. In this paper, we reviewed the current research status of the correlation between T2DM and intestinal flora.