The theory of "linkage between spleen and small intestine" has been put forward by doctors as early as the Ming dynasty. In traditional Chinese medicine， the spleen and small intestine cooperate and work together physiologically， and they are also closely related and interact with each other pathologically. The spleen governs transportation and transformation， which involves the function of the small intestine in transforming water and grain. The small intestine， governing the receiving and transformation of substances， depends on the normal transportation of the spleen. At the same time， it provides guarantee for the spleen to transform Qi and generate blood as well as ascend lucidity and descend turbidity. The dysfunction of spleen in transportation is closely related to the dysfunction of small intestine. The stability of intestinal microecology necessitates the normal functioning of the spleen. When the original balance of intestinal flora is disturbed， the spleen functioning will be affected. This study explored the pathogenesis and treatment of diabetes based on the physiological functions of the spleen and small intestine and the Western medicine targets of "nutrients-intestinal flora". According to modern medicine， nutrients are essential to maintain the normal physiological activities of the human body. Proper intake of nutrients can affect the absorption and metabolism of the human body for nutrients by regulating the composition and function of intestinal flora， so as to prevent the occurrence of diabetes. The imbalance of intestinal flora which harbors rich microorganisms may lead to the disturbance of energy metabolism and the dysfunction of the immune system， eventually leading to diabetes. As a metabolic disease， diabetes is closely related to the imbalance of intestinal flora and nutrient intake. Based on the theory of "linkage between spleen and small intestine"， this paper discusses the relationship between spleen and small intestine. Furthermore， this paper discusses the correlation between "spleen-small intestine" and "nutrients-intestinal flora" by reviewing the latest progress in modern medicine and clinical research， aiming to provide a theoretical basis and new ideas for the clinical prevention and treatment of type 2 diabetes mellitus.

The occurrence of diabetes mellitus （DM） is closely related to insulin resistance and islet β cell dysfunction. Modern studies have found that macrophages are widely present in the liver，fat，skeletal muscle，islets， and other tissues and organs. Macrophage M1/M2 polarization plays an important role in the occurrence and development of diabetes mellitus and its related complications by intervening in inflammatory response，improving insulin resistance，and promoting tissue repair. Most of the traditional Chinese medicines that regulate the activation and polarization of macrophages are Qi-replenishing and Yin-nourishing，heat-clearing， and detoxicating medicinal，which are consistent with the etiology and pathogenesis of diabetes and its related complications. Therefore，by summarizing the mechanisms between macrophage activation，polarization， and insulin resistance in various tissues，this paper reviewed traditional Chinese medicine and its effective components and compounds in improving diabetes mellitus and its related complications through multi-channel regulation of macrophage polarization and regulation of M1/M2 ratio，providing references for the future treatment of DM and its related complications with traditional Chinese medicine.