Preoperative Gastric Volume and High-Risk Gastric Content in Patients With Type 2 Diabetes Mellitus

This is a single-center, prospective observational study involving adult patients with type 2 diabetes mellitus scheduled for elective surgery.

On the day of surgery, participants will be evaluated in the preoperative preparation area before anesthesia induction and before administration of sedative premedication. Demographic data, diabetes duration and treatment, diabetes-related complications, comorbidities, smoking status, symptoms potentially associated with gastroparesis, fasting duration, and routinely available laboratory parameters will be recorded.

Capillary fasting blood glucose will be measured immediately before gastric ultrasonography and will constitute the primary independent variable.

Gastric ultrasonography will be performed by a trained and experienced investigator using a low-frequency convex transducer. The gastric antrum will be assessed first in the supine position and then in the right lateral decubitus position. Gastric contents will be classified as empty, clear fluid, or solid content. Clear fluid findings will additionally be classified according to the Perlas grading system.

For quantitative assessment, anteroposterior and craniocaudal diameters of the gastric antrum will be measured and the antral cross-sectional area will be calculated. Estimated gastric volume will be calculated from the right lateral decubitus antral cross-sectional area and expressed both in mL and mL/kg.

A high-risk stomach will be defined by at least one of the following findings: solid gastric contents, clear fluid visible in both the supine and right lateral decubitus positions (Perlas Grade 2), or estimated gastric volume greater than 1.5 mL/kg.

No experimental treatment or additional invasive intervention will be administered as part of the study. If clinically relevant high-risk gastric findings are identified, the responsible anesthesia team will be informed and subsequent anesthetic management will be determined by the clinical team.

Inclusion criteria

• Age 18 years or older
• Diagnosis of type 2 diabetes mellitus
• American Society of Anesthesiologists (ASA) physical status II or III
• Scheduled for elective surgery
• Suitable for preoperative gastric ultrasonography
• Provision of written informed consent

Exclusion criteria

• Pregnancy
• Body mass index ≥40 kg/m²
• Emergency surgery
• History of gastric, esophageal, or upper gastrointestinal surgery
• Presence of a nasogastric tube
• Known gastroparesis or gastric outlet obstruction
• Active vomiting
• Systemic opioid or prokinetic drug use within the previous 72 hours
• Anatomical or technical conditions preventing adequate gastric ultrasonographic assessment
• Impaired consciousness or inability to provide a reliable medical history
• Refusal to participate in the study