Vitamin C and libre 3 ** it looks like 15-20 higher after a few days off my supplements / C ** @Brian Wiley I’m wearing one for a couple weeks It turns out vitamin C can mess with your readings on some sugar checks My readings are a little high so I’m stopping some supplements for a few days to see if that’s the issue To ChatGPT I read somewhere vitamin C throws off blood sugar readings Response Yes, that’s correct — vitamin C (ascorbic acid) can sometimes interfere with blood sugar readings, depending on the type of glucose monitor being used. How Vitamin C Affects Readings • Fingerstick glucose meters (capillary blood): Some meters, especially older or certain models that use specific enzymatic methods (like glucose dehydrogenase–pyrroloquinoline quinone [GDH-PQQ]), may show falsely high or falsely low readings if high doses of vitamin C are in your bloodstream. • Continuous glucose monitors (CGMs): Vitamin C can also interfere with interstitial fluid sensors in some brands. For example, Abbott’s FreeStyle Libre systems have warnings that large supplemental doses of vitamin C may cause falsely elevated readings. • Laboratory blood draws: Standard lab chemistry panels (using plasma glucose) are not usually affected by vitamin C at normal supplemental levels. When It’s Most Noticeable • If you’re taking high-dose vitamin C (e.g., 1,000 mg or more at once), the risk of skewed glucose readings is greater. • People taking smaller doses (like 250–500 mg daily) are less likely to notice any effect, but it can still occur with sensitive devices. What You Can Do • Check your device manual: Many manufacturers publish lists of substances (like vitamin C, acetaminophen, uric acid) that can interfere with readings. • Compare with lab values: If your fingerstick or CGM readings seem “off” while taking vitamin C, you might ask your doctor to compare them against a lab glucose test. • Time your dose: Some people avoid taking vitamin C right before checking glucose, especially if using a CGM prone to interference. Got it — so you’re taking about 1,000 mg total per day, split into two 500 mg doses. At that dosage: • Fingerstick meters – The chance of interference depends on the exact meter model. Some older models (or ones that use GDH-PQQ enzyme strips) may still show artificially high or low readings when vitamin C is circulating in your blood. • Continuous glucose monitors (CGMs) – Systems like the Abbott FreeStyle Libre specifically warn that vitamin C at doses of 500 mg or more per day can cause falsely elevated glucose readings. So at your intake (1,000 mg/day), you could definitely see an effect if you’re on one of these devices. • Lab blood draws – Standard hospital/clinic lab tests are generally unaffected by vitamin C at this level. 👉 If you’re mainly checking with a fingerstick meter, it may or may not be an issue, depending on the strip chemistry. If you’re using a Libre CGM, your readings could look higher than they really are. Do you want me to look up the interference info for your specific meter/CGM brand so you’ll know whether 1,000 mg/day vitamin C could skew your results? Thanks — that helps a lot. Since you’re on the FreeStyle Libre 3+, here’s what’s important to know: Vitamin C and Libre 3+ • Abbott (the manufacturer) specifically warns that taking more than 500 mg/day of vitamin C can cause the Libre system to show falsely high glucose readings. • You’re taking 1,000 mg/day, so it’s very possible that your Libre readings are reading higher than your actual blood glucose. • This doesn’t mean the sensor is broken — it’s a known chemical interference in the way the sensor enzyme detects glucose in the interstitial fluid. What That Means for You • If your Libre is showing a baseline around 115 mg/dL, your true blood sugar might be somewhat lower (maybe 5–20 points, though it varies). • The only way to know for sure is to cross-check with a fingerstick meter (ideally one that isn’t affected by vitamin C) — at least a few times while you’re supplementing. • Labs will always give you the most accurate number, since they’re not affected by vitamin C. Practical Options 1. Keep taking vitamin C and just remember your Libre might read a little high. 2. Do spot fingersticks at different times of day (fasting, after meals) to compare with Libre. 3. Pause/reduce vitamin C temporarily if your main goal is absolute accuracy with Libre data during these 2 weeks. Would you like me to pull up Abbott’s exact wording from the Libre 3+ manual about vitamin C so you can see the official recommendation?

Posted by Pastor Gary at 2025-09-28 12:23:15 UTC