Diabetes is a chronic metabolic disease characterized by changes in the dynamic balance of blood glucose levels. Subcutaneous injection of insulin is a first-line treatment for diabetes. However, patient compliance is poor due to pain, discomfort, and local infection. Oral administration is convenient and safe, but the existing oral insulin preparations still need to be optimized due to gastrointestinal instability and poor bioavailability. The rapid development of nano-preparation technology provides a solid foundation for improving the bioavailability of oral insulin preparations and achieving the effective oral delivery of insulin. This paper reviews the research progress in insulin nanoparticles with high oral bioavailability in recent years.