Continuous Glucose Monitoring

Non‑invasive wearables & future tech

• Several comments hope for bloodless glucose monitoring in mainstream wearables (e.g., smartwatches).
• Current optical/“no-prick” consumer devices are described as highly inaccurate; an FDA warning is cited and some say they’re no better than random numbers.
• Apple/Samsung are rumored to be working on non‑invasive glucose, but commenters expect blood pressure to arrive first in mass-market watches.
• Existing CGMs like Dexcom measure interstitial fluid with a 5–15 minute lag but are seen as dramatically better than finger pricks.

Accuracy, delays & what matters

• Reported accuracy ranges from ~8% MARD for top CGMs to much worse for some meters; a 20% error is seen as plausible for low-end devices.
• Several diabetics note both CGMs and finger sticks can disagree by ~20%, but trends and alarms are more important than exact numbers.
• There’s consensus that CGMs can misread, especially new sensors, and unexpected results should be confirmed with a finger stick.

Costs, hardware & wear issues

• A teardown suggests sensor BOM around a few dollars, but commenters stress pricing is driven by R&D, regulatory requirements, quality control, and replacement support.
• Adhesive failure, skin irritation, and sensor chemical wear limit wear time (often 10–14 days), though some “hacked” setups stretch this to ~20–25 days with over‑patches.
• Pet use (e.g., diabetic cats) is possible but expensive and less reliable.

Dietary insights & debates

• Non‑diabetic users report learning which foods cause spikes (white bread, croissants, dried fruit, juices, sweet breads) and how sequencing (fiber/fat/protein first) and post‑meal movement blunt peaks.
• Others worry this encourages over‑optimization of a single metric, cutting out otherwise reasonable foods, and drifting toward orthorexia.
• Long‑term harm of glycemic spikes in non‑diabetics is debated: some cite strong medical concern; others say evidence is mostly correlational and confounded by overeating and ultra‑processed diets.

Non‑diabetics vs diabetics

• A number of healthy users found CGMs “interesting but useless” once they saw their glucose stayed within normal bounds.
• Others say short stints (weeks) were transformative for understanding hunger, crashes, and meal composition.
• Multiple comments argue CGMs are truly essential for type 1 diabetes (and some type 2 on insulin), but largely unnecessary for most healthy people.

Exercise & metabolism feedback

• Users report weightlifting spikes glucose, intense cardio can drop it sharply, and CGMs revealed hypoglycemia as a cause of workout exhaustion for some.
• Others emphasize this doesn’t make hard exercise “unhealthy”; it just shows the need for intra‑workout carbs or attention to glycogen stores.
• Discussion touches on liver glycogen release and finite counter‑regulation, especially in type 2 diabetes.

Software ecosystem & access

• Third‑party apps like Juggluco, Nightscout, and xDrip+ are praised for data export, remote viewing, and richer analytics than official apps.
• Abbott’s region‑locked Libre app (e.g., lack of alerts/integration in Brazil) is criticized; cause (regulation vs legal caution) is unclear.

Skepticism & open questions

• Some see CGMs for non‑diabetics as “geek bait” akin to step counters, with unclear long‑term benefit and a risk of obsession.
• There’s interest in continuous combined glucose/ketone monitoring, but no clear answers on commercially viable solutions in the thread.