The 3-hour postprandial blood glucose is not used as a diagnostic criterion for diabetes. Although the 3-hour postprandial blood glucose level will return to the fasting blood glucose level, it is mostly recognized as the 3-hour postprandial blood glucose as random blood glucose. It is recommended that fasting blood glucose and 2-hour postprandial blood glucose be tested under the supervision of a physician. In general, diabetes mellitus is determined by the presence of typical symptoms of diabetes mellitus, i.e., excessive eating, drinking, urination and weight loss, coupled with the presence of fasting blood glucose ≥ 7 mmol/L, or 2-hour postprandial blood glucose ≥ 11.1 mmol/L, or random blood glucose ≥ 11.1 mmol/L, or glycated hemoglobin ≥ 6.5%, and diabetes mellitus is considered to be diabetes mellitus when one of the above values is met. Anyone with high blood glucose should consult an endocrinologist in a timely manner and receive regular treatment under the guidance of a doctor. It is also necessary to actively control blood glucose through exercise and improving dietary structure.