People with diabetes don’t have higher gastric volumes than those without diabetes after following standard preoperative fasting instructions, suggested a study from a team of anesthesiologist researchers.
Moreover, the issue is now further complicated by the widespread use of glucagon-like peptide-1 (GLP-1) receptor agonists for the treatment of both type 2 diabetes and weight loss. These drugs, which were introduced after the study’s enrollment period, work in part by delaying gastric emptying.
The new data come from a prospective study of 84 people with diabetes (85% with type 2) and 96 without diabetes, all with a body mass index (BMI) < 40, who were undergoing elective surgery. A gastric ultrasound was used to assess their gastric contents after they had followed the standard preoperative fasting guidelines of stopping solids 8 hours prior to the procedure and clearing liquids 2 hours prior.
There was no significant difference between the two groups in gastric volume (0.81 mL/kg with diabetes vs 0.87 mL/kg without) or in the proportion with “full stomach,” as designated by the American Society of Anesthesiologists (ASA) guidelines (any solid content or > 1.5 mL/kg of clear fluid), which was seen in 13 with diabetes (15.5%) and 11 (11.5%) without.
Published in Anesthesiology, the findings offer reassurance that different fasting instructions generally aren’t needed for people with diabetes in order to minimize the risk for perioperative pulmonary aspiration, lead author Anahi Perlas, MD, professor of anesthesiology and pain medicine at the University of Toronto, told this news organization.
“We never change practice completely based on a single study, but I think in general, based on our findings, that most diabetic patients aren’t any different from nondiabetics when it comes to their gastric content after fasting, and our standard fasting instructions seem to be just as effective in ensuring an empty stomach.”
But, she added, “If someone has symptoms of gastroparesis or when in doubt, we can always do a gastric ultrasound exam at the bedside and see whether the stomach is full or empty ... it’s very quick, and it’s not difficult to do.”
Expert Identifies Noteworthy Study Limitations
In an accompanying editorial, Mark A. Warner, MD, professor of anesthesiology at the Mayo Clinic in Rochester, Minnesota, said the findings “will be very helpful to anesthesiologists,” although he noted that the exclusion of people with a BMI > 40 is a limitation.
However, Michael Horowitz, MBBS, PhD, FRACP, director of the Endocrine and Metabolic Unit at the Royal Adelaide Hospital and professor of medicine at Adelaide Medical School in Adelaide, Australia, disputed the study’s conclusions. He noted that the sample was small, and the participants had an average A1c of 7.2%. Fewer than half had microvascular or neuropathic complications. Thus, they were healthier than the general population with diabetes.
“They’ve picked the wrong group of diabetics,” said Dr. Horowitz, who specializes in gastrointestinal complications of diabetes. “This is not a group where you would expect a very high prevalence of delayed emptying.”
Gastric emptying of solids and liquids varies widely even among healthy people and more so in those with type 2 diabetes. About a third of those with above-target A1c levels have gastroparesis, while those more in the target range tend to have accelerated emptying, he explained.
And regarding the use of gastric ultrasound for those who are symptomatic, Dr. Horowitz said, “The relationship of symptoms such as nausea, vomiting, fullness, whatever it may be, with the rate of gastric emptying is weak at best. The association is not simply cause and effect.”