Approximately 3% to 4% of the U.S. adult population has undiagnosed diabetes and the prevalence is likely to be substantially higher among people with risk factors for diabetes. Of note, many patients at the time of diagnosis of diabetes already have diabetic complications. This indicates that there is a period of "asymptomatic" diabetes during which hyperglycemia and other risk factors are present and complications are developing. This substantial delay in clinical diagnosis of diabetes involves a period of about 10-12 years that elapses between onset of diabetes and its diagnosis. Early diagnosis of diabetes, with treatment aiming at strict control of blood glucose levels, is important in preventing or mitigating its clinical complications and improving health outcomes.