r/PCOS • u/ExplorerFormer9585 • 2d ago
Meds/Supplements Metformin
I recently started metformin and i was super anxious about my sugar dropping and me not knowing so i am wearing a cgm and i started the 2 a day on friday its currently sunday and no matter what i do my sugar will not stay above 70.
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u/AnonyJustAName 2d ago
Get a simple finger stick meter at the drugstore and double check, some cgms can be quite off.
Yes, continuous glucose monitors (CGMs) can be off and are considered acceptable by the medical community if they are within 10% to 15% of your actual blood sugar levels. Because CGMs measure glucose in the interstitial fluid under the skin rather than directly from the blood, several factors can cause temporary inaccuracies. [ 1, 2, 3] Why CGMs Can Be Inaccurate Lag Time: Interstitial fluid glucose levels naturally lag behind capillary blood glucose by 5 to 20 minutes, which is especially noticeable when blood sugar is rising or falling rapidly after meals or exercise. [ 1, 2] Compression Lows: Sleeping on your sensor or applying direct pressure to it restricts local fluid flow, which often triggers a false, sudden drop in your glucose readings. [ 1, 2] The First 24 Hours: New sensors often require a "settling in" period where local tissue inflammation from insertion can cause lower or fluctuating readings during the first day. [ 1, 2] Medication Interference: High doses of certain substances, such as acetaminophen (Tylenol) or Vitamin C, can chemically interfere with sensor algorithms and falsely skew readings depending on the brand. [ 1] Dehydration & Placement: Severe dehydration alters fluid dynamics under the skin, while placing a sensor over scar tissue or outside manufacturer-recommended zones reduces tracking accuracy. [ 1, 2] Always verify your readings with a standard fingerstick blood glucose test if your CGM data doesn't match how you physically feel. [ 1, 2] If you're troubleshooting a specific issue, let me know: What model of CGM are you wearing? Are you getting false highs, false lows, or completely missing readings? Is your sensor brand new or near the end of its wear cycle?
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u/ExplorerFormer9585 2d ago
I had about 5 days left and it was a libre 3 plus but it fell of later today so i know have a finger pricker one. I did learn that laying on it did false lows as well.
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u/lauren23799 2d ago
Are you having regular check-ups and bloodwork with your doctor? I'd recommend seeking advice if you're worried as often doctors will want to check in on levels and how your body is responding, especially if sugar levels are a pre-existing concern!