To the editor:

Your Ask the Expert article in the December 2022 issue of CLN, Mitigating Test Interference From Antioxidant Vitamins, was an excellent piece about an important topic. Dr. Vrajesh Pandya discussed several salient points about this subject. Interferences are becoming more commonplace, especially in critically ill patients, and vitamin C in particular is being used increasingly for many different conditions including sepsis, burns, and oncology, among others. Dr. Pandya noted that these antioxidant vitamins, including vitamin C, affect redox reactions and can interfere with results.

One such reaction that is one of the most common tests performed in the hospital is testing for glucose using a point-of-care (POC) meter. Vitamin C is a well-known interfering agent with POC glucose devices; it can cause factitious hyperglycemia and the potential for negative outcomes from inappropriate insulin administration. There have now been numerous case reports of deaths and devastating consequences from erroneous glucose readings due to vitamin C interference (1-6), so this is not just a theoretical problem. It is also not a new problem—in 2010 the Food and Drug Administration (FDA) noted that there were 100 deaths and over 12,000 serious injuries associated with blood glucose monitoring system errors (7).

Glucose monitoring therefore deserves special attention in any discussion about antioxidant interferences because of its high frequency of use and potential for serious adverse outcomes. There are POC glucose meters which have been shown to not be susceptible to this (or any) interferences, and which have been approved by the FDA for use in all hospitalized patients (8). Knowledge of potential errors from interfering agents and, more importantly, how to avoid them, is an important issue for all healthcare providers to be aware of. Thank you for highlighting this critically important topic and increasing awareness of the problem.

Dennis Begos, MD, is senior medical director of medical and scientific affairs at Nova Biomedical. +Email: [email protected]


1. Berge DT, Manning F, Silderhuis V, et al. Delayed Diagnosis of Severe Hypoglycemia in a Septic Patient With Chronic Renal Failure. Cureus 2022; doi:10.7759/cureus.28615.

2. Berge DT, Muller W, Beishuizen A, et al. Significant interference on specific point-of-care glucose measurements due to high dose of intravenous vitamin C therapy in critically ill patients. Clin Chem Lab Med 2021; doi: 10.1515/cclm-2020-1445.

3. Orija IB, Zahid SH. Pseudohyperglycemia Secondary to High-Dose Intravenous Vitamin C Managed as Diabetic Ketoacidosis: An Endocrinological Catastrophe. AACE Clin Case Rep 2021; doi: 10.1016/j.aace.2020.11.030

4. Lachance O, Goyer F, Adjikari NJK, et al. High-dose vitamin-C induced prolonged factitious hyperglycemia in a peritoneal dialysis patient: a case report. J Med Case Rep 2021. doi: 10.1186/s13256-021-02869-4.

5. Zhang Y, Huang W. Never a rose without a prick: pseudohyperglycemia when administering high-dose intravenous vitamin C. Crit Care 2020; doi: 10.1186/s13054-020-02994-4.

6. Katzman BM, Kelley BR, Deobald GR, et al. Unintended Consequence of High-Dose Vitamin C Therapy for an Oncology Patient: Evaluation of Ascorbic Acid Interference With Three Hospital-Use Glucose Meters. J Diabetes Sci Technol 2020;  doi: 10.1177/1932296820932186.

7. FDA, U.S., Clinical Accuracy Requirements for Point of Care Blood Glucose Meters; Public Meeting; Request for Comments. (Accessed January 2010).

8. DuBois J, Malic A. The StatStrip Glucose Hospital Meter System. Point-of-care testing in critically ill patients. Point of Care: The Journal of Near-Patient Testing & Technology 2017; doi:10.1097/POC.0000000000000127