Recent research suggests that people with diabetes do not need to fast longer before surgery compared to those without diabetes. This study, led by a team of anesthesiologists, found no significant difference in gastric volumes between diabetic and non-diabetic patients after following standard preoperative fasting guidelines.
Study Overview
The study involved 180 participants, including 84 people with diabetes (primarily type 2) and 96 without, all with a body mass index (BMI) of less than 40. These individuals were undergoing elective surgery and adhered to the standard preoperative fasting guidelines: no solid food for 8 hours and only clear liquids up to 2 hours before the procedure. Gastric ultrasound was used to measure their gastric contents.
The results showed minimal difference in gastric volumes between the two groups, with diabetic patients having an average gastric volume of 0.81 mL/kg compared to 0.87 mL/kg in non-diabetic patients. The proportion of individuals with “full stomachs” (as defined by the American Society of Anesthesiologists (ASA) guidelines) was also similar: 15.5% in diabetic patients and 11.5% in non-diabetic patients.
Implications and Expert Opinions
These findings, published in Anesthesiology, suggest that diabetic patients do not generally require different fasting instructions to minimize the risk of perioperative pulmonary aspiration. Lead author Dr. Anahi Perlas of the University of Toronto stated that standard fasting instructions appear effective for diabetic patients, though she noted the value of gastric ultrasound for patients with symptoms of gastroparesis or when there is uncertainty about gastric emptying.
However, some experts have criticized the study. Dr. Michael Horowitz, a specialist in gastrointestinal complications of diabetes, pointed out that the study participants were healthier than the typical diabetic population, with an average A1c of 7.2% and fewer complications. He argued that the study’s conclusions might not apply to the broader diabetic population, particularly those with more severe or uncontrolled diabetes.
Complications with GLP-1 Receptor Agonists
The study did not consider the impact of glucagon-like peptide-1 (GLP-1) receptor agonists, a class of medications increasingly used for type 2 diabetes and weight loss. These drugs, which were introduced after the study’s enrollment period, delay gastric emptying, potentially complicating fasting guidelines for diabetic patients.
Dr. Mark A. Warner of the Mayo Clinic highlighted this issue in an accompanying editorial, noting that GLP-1 agonists could alter the application of fasting guidelines due to their impact on gastric emptying times. He endorsed the 2023 ASA guidelines, which recommend withholding daily-dosed GLP-1 agonists on the day of surgery and weekly formulations for a week. Yet, Dr. Horowitz argued that these recommendations might be insufficient, as some studies suggest that the effects of these drugs on gastric emptying can last much longer than currently appreciated.
Reevaluating Fasting Guidelines
Dr. Horowitz also criticized the ASA’s 2017 guidance, which allows clear liquids up to 2 hours before anesthesia, for not distinguishing between caloric and non-caloric liquids. He suggested that this could explain the relatively high rates of “full stomachs” found in both study groups.
The study raises important questions about the adequacy of current fasting guidelines for both diabetic and non-diabetic patients, particularly in light of new medications like GLP-1 receptor agonists. While gastric ultrasound can be a useful tool for assessing gastric contents preoperatively, more research is needed to develop tailored fasting recommendations that account for these factors.
The findings from this study offer reassurance that standard fasting guidelines are generally effective for diabetic patients, but also underscore the need for individualized assessment, especially for those with gastroparesis or on medications affecting gastric emptying. As medical treatments and understanding of diabetes evolve, so too must the guidelines ensuring patient safety during surgery.