Continuous monitoring of blood glucose levels is a prerequisite for controlling diabetes and its complications. Noninvasive methods have attracted great attention for their lack of injury and widespread acceptance. With the improvement of measurement accuracy in recent decades, optics-based methods of noninvasive blood glucose detection have shown great potential in clinical applications. In this paper, the main optics-based methods of noninvasive blood glucose detection, such as polarimetry, optical coherence tomography and infrared spectroscopy, are reviewed with regards to their principles, advantages, accuracy, problems and the possible solutions to those problems. By comparison, it concludes that the method of infrared spectroscopy has obvious advantages in detection accuracy. In the future, major challenges will be in increasing the signal-to-noise ratio of instruments, eliminating background interference and establishing universal calibration models.