Environmental Impact of Disposable CGM Electronics

Introduction

Every disposable CGM sensor that goes in the trash takes a small electronics package with it. A German team took 24 used sensors apart in 2024 and found the same three parts in each: a plastic case, a printed circuit board (PCB, the small board that holds the chips) and a battery [1]. The batteries are mostly zinc-silver oxide or lithium-ion cells [1]. Scaled up to about 230 million sensors used worldwide each year, the authors estimated about 580 tons of discarded sensors annually, including about 130 tons of circuit boards and 110 tons of batteries [1].

Here's what surprised us: the electronics are not the heaviest part. Packaging plus the applicator and leaflet weighed 58 to 108 grams per sensor, depending on the model, while the sensors themselves weighed 1.1 to 3.3 grams [1]. Worldwide, that adds up to about 20,000 tons a year [1].

Current State of CGM Technology

As of October 2026, the main prescription sensors from Dexcom and Abbott have the electronics built in. The board and battery are thrown away with each sensor. Dexcom describes both the Dexcom G7 (10-day) and the Dexcom G7 15 Day as an "all-in-one sensor and transmitter" [3]. Abbott's current sensors are the FreeStyle Libre 3 Plus and Libre 2 Plus, worn up to 15 days; the earlier Libre 3 and Libre 2 sensors were available only through September 30, 2025 [5].

Older designs split the parts. The Dexcom G6 used a transmitter that clipped onto each new sensor and was reused, and the FDA's review states its battery was designed to last 3 months [4]. Dexcom stopped manufacturing the G6 after July 1, 2026 [3]. Its transition page directs G6 users to the G7 sensors [3]. One G6 transmitter's board and battery served several sensors. An all-in-one design sends a new board and battery out with every sensor; in the German teardown, a used G7 held about 0.7 g of circuit board and 0.6 g of battery [1].

Used sensors often skip electronics recycling altogether. Most participants in the German study had been told to put used sensors in household waste, and the adhesives in the G7 made full separation of its parts nearly impossible, which works against recycling [1]. A Finnish life cycle study made the same assumption, modeling used CGMs as going to incineration or mixed municipal waste [6].

Environmental Impact Assessment

Life cycle assessment (LCA) counts a product's environmental cost from raw materials through disposal. A 2025 cradle-to-grave LCA from the Finnish Environment Institute compared two CGMs with four fingerstick meter setups over one year of use, assuming 26 sensors a year at 14 days each [6]. The two CGMs came to about 34.6 and 27.7 kg of CO2-equivalent per year [6]. Counting strips and lancets, the fingerstick setups came to 7.0 to 9.6 kg [6]. Fingerstick testing stayed lower unless someone tested more often than usual or used the device for a shorter period than average [6].

The electronics were not the biggest factor. Plastic parts and the paper instruction leaflet led for both CGMs, and printed circuit boards ranked third, at 16% and 11% of the footprint [6]. One leaflet weighed 242 grams and made up 49% of its device's footprint [6]. The study measured carbon only and identified the devices only as "CGM-1" and "CGM-2" [6], so it can't tell us how a specific current sensor compares. It also isn't a reason to switch monitoring methods; which method fits you is a decision for your care team.

Innovations and Future Directions

Implantable sensors cut the number of devices thrown away. As of October 2026, the current implantable CGM is the Eversense 365: a clinician places the sensor under the skin, where it reads glucose for up to 1 year, and an external smart transmitter worn over it is charged daily and has a battery designed to last 12 months [7]. The Eversense E3 it replaced was rated for up to 6 months. Longer wear periods are one of the waste reductions the German team recommends [1]. We found no study that measures Eversense waste directly, though. The system still needs fingerstick calibrations, weekly after the first two weeks [7], and lancets were the largest carbon contributor for fingerstick testing in the Finnish LCA [6].

Two research directions aim at the battery and the board themselves. An enzymatic biofuel cell uses enzymes to draw electrical energy from body fluids such as blood or interstitial fluid. A 2025 review describes prototypes that power wearable and implantable biosensors this way, and lists low power density, short operating life and miniaturization as unsolved problems [8]. Biodegradable, or "transient," electronics go further: a 2012 Science paper reported silicon circuits, sensors and power components designed to dissolve and be resorbed by the body after a set time [2]. Neither approach has reached a commercial CGM in the sources we reviewed. A 2025 commentary adds a practical obstacle: medical device rules that rightly prioritize sterility and safety make it slow to bring recycled or biodegradable materials into a device [9].

Conclusion

By weight, most CGM waste is the packaging, applicator and leaflet around the sensor, not the circuit board inside it [1]. That makes the nearest fixes less exotic than biofuel cells. The Finnish authors point to reusable or lighter applicators and digital instructions [6], and the German team adds smaller sensors and less packaging [1]. Recovering the board and battery from each used sensor is the part with no clear route yet, and the German team lists recycling options as an unmet need [1].