• Group C: will receive a carbohydrate drink of 400 ml (50 g of glucose prepared by nutrition division, same appearance and containing bottles of water)
• Group W: will receive water 400 ml (prepared by nutrition division, Songklanagarind hospital, same appearance and containing bottles of carbohydrate drink) In both groups, the received 400-mL drink was consumed within 5 minutes.
• Before drinking, baseline data (gastric residual volume, POCT glucose, degree of hunger, and thirst) will be evaluated.
• Gastric ultrasound will be performed by the same Radiologist on each participant at 0, 30, 60, 90, 120 minutes
• after drinking to evaluate the gastric residual volume and time to empty gastric antrum.
• POCT glucose and degree of hunger and thirst are also assessed again at 120 minutes after drinking.
• After completing one type of drinking, participants will be appointed again after 1 week later for doing the same protocol with another drinking.

changes in gastric residual volume during 2 hours after drinking

changes in glucose level after ingest carbohydrate drink or water