On September 23, 2025, friend and colleague Dave McGlasson had a fasting blood specimen drawn. The collector noted that he was chewing gum and explained that the gum, although sugar-free, could affect the results. McGlasson messaged, “Chewing sugar-free gum should be avoided before a fasting blood draw because it can elevate certain blood levels, including cortisol, insulin, and GLP-1, and can impact other metrics like triglycerides and amylase. While sugar-free gum doesn’t contain significant calories, the act of chewing itself triggers physiological changes that can affect test results, making it best to avoid gum altogether to ensure accuracy.” Click this open-access article for details. (Note that gum doesn’t affect coag results): Stonys R, Banys V, Vitkus D, Lima-Oliveira G. Can chewing gum be another source of preanalytical variability in fasting outpatients? JIFCC. 2020;31:28-45. PMID: 32256287; PMCID: PMC7109498.
Abstract
Introduction: In the daily laboratory practice, there are patients coming to blood collection sites chewing sugar-free gum, considering it irrelevant to laboratory tests. The aim of this study was to evaluate whether a sugar-free chewing gum can interfere with laboratory tests.
Methods: We studied 22 healthy volunteers. After a 12-hour overnight fasting, the first blood sample was collected between 8:00 and 8:30 a.m. Then, immediately after the first venous blood collection, the subjects started chewing the gum (declared sugar-free) for 20 min. Subsequent venous blood samples were collected at 1, 2, and 4 hours after chewing the gum. Significant differences between samples were assessed by the Wilcoxon ranked-pairs test.
Results: Among all the results, statistically significant differences (p < 0.05) between basal and × hours after chewing sugar-free gum were observed for the following parameters: cortisol, insulin, C-peptide, triglycerides, uric acid, urea, amylase, alanine aminotransferase, lipase, creatine kinase, total bilirubin, direct bilirubin, phosphate, iron, potassium, thyroid stimulating hormone, red blood cell count, hematocrit, hemoglobin, mean cell volume, red cell distribution width, white blood cell count, lymphocytes, neutrophils, and eosinophils; whereas, coagulation tests were not impacted by chewing sugar-free gum.
Conclusions: We recommend instructing the patients to avoid the use of chewing gum before blood collection for laboratory tests.
Keywords: blood specimen collection; diagnostic errors; fasting; postprandial period; reproducibility of results.
Well maybe… Stress is known to increase various blood analytes; for hemostasis, fibrinogen, FVIII and von Willebrand factor are good examples. So, if chewing gum alleviates stress, would it be more advantageous to have a stress free fasting level rather than a stess-induced increased in stress related markers from the fear of the venipuncture? Just throwing it out there…