Prediabetes is considered to be one of the most insidious precursors to diabetes because it may not have any signs or symptoms. This is why it is so important to do diagnostic blood tests checking a fasting glucose or hemoglobin A1c (HbA1c) test to establish a diagnosis of prediabetes. Many people who have prediabetes (which affects 84 million adults in the U.S.) do not have any symptoms. By the time symptoms occurs, the diagnosis has usually already progressed to diabetes. There are some rare situations in which an individual can present with diabetes-related complications such as a retinal bleed, neuropathy or even a stroke, while only having a diagnosis of prediabetes.