Ultrasonographic assessment of residual gastric volume indiabetic versus non-diabetic patients following standard preoperative fasting: A comparative observational study

Background: Pulmonary aspiration of gastric contents at induction of anaesthesia is uncommon but carries substantial morbidity and mortality. Standard fasting intervals assume normal gastric emptying, yet diabetes mellitus is among the commonest causes of delayed emptying and diabetic gastroparesis is frequently asymptomatic. Point-of-care gastric ultrasonography permits bedside assessment of residual gastric volume. Methods: A prospective comparative observational study enrolled 160 adults undergoing elective surgery under general anaesthesia, in two groups of 80 defined by the presence or absence of diabetes mellitus. After fasting according to American Society of Anesthesiologists guidance, the gastric antrum was imaged with a 2–5 MHz curvilinear probe in the supine and right lateral decubitus positions. Antral cross-sectional area was calculated from orthogonal antral diameters and gastric volume estimated using the validated Perlas model. Perlas gastric grade and the proportion with a volume of 1.5 mL/kg or more were compared between groups. Results: Diabetic patients showed a larger mean antral cross-sectional area (7.8 ± 2.2 versus 5.0 ± 1.4 cm², p < 0.001) and a larger estimated residual gastric volume (70 ± 27 versus 37 ± 18 mL, p < 0.001) than non-diabetic patients despite identical fasting protocols. The distribution of Perlas gastric grades differed between groups (p < 0.001), with grade 2 antra in 22.5% of diabetic and 5.0% of non-diabetic patients. A gastric volume of 1.5 mL/kg or more was recorded in 23.7% of diabetic patients and 1.2% of non-diabetic patients (p < 0.001). Within the diabetic group, residual gastric volume correlated with glycated haemoglobin (r = 0.42, p < 0.001) and with duration of diabetes (r = 0.39, p < 0.001). Conclusion: Diabetic patients retained greater gastric contents than non-diabetic patients despite recommended fasting durations. Gastric ultrasonography offers a rapid, non-invasive method of individualised aspiration risk assessment and may inform perioperative decision-making in this group.