INS and diabetes mellitus: The American Diabetes Association Guidelines 2021 suggests that PPG monitoring should be conducted in patients with diabetes who failed to reach satisfactory HbA1c levels but obtained target fasting blood glucose, and PPG levels should be maintained below 10.0 mmol/L to reduce HbA1c.[16] Gastric emptying, intestinal proinsulin system, and preprandial blood glucose levels affect postprandial blood glucose levels.