Abstract: High-sugar diet causes various diseases, including insulin resistance, diabetes, and non-alcoholic fatty liver disease (NAFLD). In recent years, as researchers probe deeper and deeper into issues concerning high-sugar diet, the impact of high-sugar diet on inflammatory diseases such as autoimmune diseases and infectious diseases has been gradually uncovered and clarified. In this review, we summarized the current research progress on high-sugar diet and inflammatory diseases, and suggested that a high-sugar diet based on high intake of glucose and fructose may be an important factor inducing the exacerbation of chronic inflammatory diseases such as autoimmune diseases. Moreover, we also summarized the regulatory mechanisms through which high-sugar diet induces exacerbation of inflammatory diseases. In addition, we stated that conducting extensive clinical research and research in real-life settings and pursuing thorough investigation to reveal the different involvement of high-glucose diet and high-fructose diet in immune regulation are the key scientific issues that need urgent solutions in the future.