Vitamin D Supplementation and CGM Results
Vitamin D supplementation does not affect Continuous Glucose Monitoring (CGM) results and is not listed as an interfering substance in major clinical guidelines for CGM use. 1
Impact of Vitamin D on CGM Accuracy
Current CGM guidelines specifically mention that high-dose vitamin C (ascorbic acid) can interfere with glucose meter accuracy, but vitamin D is not listed as an interfering substance for CGM systems. 1
The American Diabetes Association's Standards of Medical Care specifically identifies "high-dose vitamin C and hypoxemia" as factors that can interfere with glucose meter accuracy, but makes no mention of vitamin D as a potential interferent. 1
Chinese Clinical Guidelines for CGM similarly do not list vitamin D among substances that can affect CGM readings, while specifically mentioning other potential interferents. 1
Known Interferents with CGM Systems
Most current CGM systems use glucose oxidase-based technology, which can be affected by certain substances including:
- Acetaminophen (at higher than therapeutic doses)
- Ascorbic acid (vitamin C)
- Uraemic toxins (in patients with kidney disease)
- Hypoxemia
- Certain medications like tetracycline and mannitol (for implantable sensors) 1
For patients with advanced chronic kidney disease, substances that may interfere with CGM readings include "lisinopril, albuterol, acetaminophen, atenolol, ascorbic acid (vitamin C) and red wine," but vitamin D is not mentioned. 1
Vitamin D and Glucose Metabolism
While vitamin D supplementation has been studied for its potential effects on glucose metabolism in patients with diabetes, these studies examine the physiological effects on glucose levels themselves, not interference with CGM measurement technology. 2, 3
Some studies suggest modest improvements in HbA1c after vitamin D supplementation in type 2 diabetes patients, but these represent actual changes in glucose metabolism rather than measurement artifacts. 4
A study examining vitamin D supplementation in vitamin D-deficient individuals without diabetes found no significant changes in glucose tolerance or insulin sensitivity, further supporting that vitamin D does not substantially alter glucose measurements. 5
Clinical Recommendations
When using CGM systems, healthcare providers should be aware of factors that can affect accuracy, including:
- Proper sensor placement and calibration
- Using the same glucose meter and test strip batch for calibration
- Avoiding areas with arteriovenous fistulas in dialysis patients
- Being aware of known interferents like high-dose vitamin C 1
For patients taking vitamin D supplements who use CGM, no special precautions are necessary regarding the accuracy of their readings based on current clinical guidelines. 1
If unexpected CGM readings occur, standard troubleshooting should include checking for proper sensor placement, calibration timing, and known interferents, but vitamin D supplementation would not be a concern. 1