Residual Gastric Volume Measured by Ultrasound in Diabetic Surgical Population Versus Non-diabetic Surgical Population.

Inclusion Criteria: * BMI\<40 kg.m-2; * Age over 18 years; * American Society of Anesthesiologists' physical status status I-III * who were to undergo elective surgery and had the ability to understand the rationale of the study and provide informed consent Exclusion Criteria: * Pregnancy * Recent upper gastrointestinal bleed (\< 1 month) * Abnormal anatomy of the upper gastrointestinal tract (such as hiatal hernias and gastric tumors) * Previous surgical procedures on the esophagus, stomach, or upper abdomen * Gastroesophageal reflux disease * Previous use of prokinetics or high doses of opiates.