Type 1 diabetes (T1D) is characterized by absolute insulin deficiency. Although the discovery and application of exogenous insulin has prolonged the lifespan of T1D patients, the chronic diabetic complications caused by long-term poor glycemic control will still reduce patients' quality of life and the overall life expectancy. According to the studies focused on long-term T1D, part of the patients with long disease duration showed resistance to microvascular complications, and several protective factors have been identified. The prevalence of T1D in China is extremely low compared to that in the western world, and little is known about the characteristics of patients with long-term T1D in China. Therefore, this study is designed to collect variable clinical and laboratory features of patients with long-term T1D, explore the risk and protective factors for the development of microvascular complications, and provide reference for the prediction and prevention of these complications.