Environmental Impact and Sustainability of Disposable Sensors

Introduction to Environmental Impact and Sustainability

Most continuous glucose monitors (CGMs) are thrown away whole at the end of each wear, and every discarded sensor carries a plastic case, a small circuit board and a coin-cell battery [2]. Here's what surprised us when we read the waste studies: the sensor is the small part. In a 2024 teardown of used FreeStyle Libre 2, FreeStyle Libre 3 and Dexcom G7 sensors, the box, single-use applicator and paper leaflet that came with each sensor weighed 58 to 108 grams, while the sensors themselves weighed about 1 to 3 grams [2]. Abbott has since replaced both Libre sensors in that study with its Libre 2 Plus and Libre 3 Plus sensors; the originals were available only through September 30, 2025 [13]. This section covers where the waste comes from and how the main sensor designs compare.

Environmental Concerns Associated with Disposable Sensors

Newer sensors use less plastic, but more of their electronics now go in the bin. A 2024 review reported that the FreeStyle Libre 3 is more than 70% smaller than earlier Libre sensors, with 41% less plastic, and that the Dexcom G7 and MiniMed's Simplera are 60% and 50% smaller than the sensors they followed [1]. The trade-off is the transmitter, the part that powers the sensor and sends readings to a phone or receiver. The Dexcom G6 paired each disposable sensor with a reusable transmitter rated for 3 months of battery life [9]; the G7 builds sensor and transmitter into one unit that is discarded after every wear [5]. Dexcom says it no longer manufactures the G6 after July 1, 2026, though some stock may stay on pharmacy shelves for a while [8].

Each of those all-in-one units holds a single-use battery. The Libre 2 and Libre 3 sensors that researchers took apart used zinc-silver oxide coin cells, and Dexcom sensors use lithium-manganese dioxide cells [1]. Scaling its teardown to an estimated 230 million sensors used worldwide each year, the 2024 study put the yearly total at about 130 tons of circuit boards and 110 tons of batteries, on top of roughly 20,000 tons of packaging, applicators and leaflets [2].

Where a used sensor ends up depends on local rules. Because it contains a contaminated sharp, a UK-based review describes Libre sensors being handled as clinical waste and incinerated [1]. In a German study, most people disposed of sensors in household waste, and the adhesives made the G7 nearly impossible to take apart, which also gets in the way of recycling [2]. Neither route sent the sensors to electronics recycling [1][2].

Comparative Analysis of CGM Systems

The number of sensors a person discards each year depends mostly on wear time. By our count from the labeled wear times, 15-day sensors such as the FreeStyle Libre 3 Plus [7], the Dexcom G7 15 Day [5] and the MiniMed Instinct sensor [6] add up to about 25 a year. The 10-day Dexcom G7 comes to about 37 [5]. MiniMed's 7-day Guardian 4 and 6-day Simplera sensors run from about 53 to 61 a year [6]. Replacements for sensors that fail or fall off add to every one of those totals [2].

Implantable sensors change that math. As of October 2026, the current Eversense model from Senseonics is the Eversense 365: a healthcare provider places one sensor under the skin with dedicated insertion tools, and it lasts up to 1 year [3]. The sensor sends its readings to an externally worn smart transmitter, and that transmitter needs charging every day [3]. Its predecessor, the Eversense E3, was approved in February 2022 for up to 180 days, or about two sensors a year [4].

On unit count alone, one implanted sensor a year is far fewer than 25 to 61 disposable ones. We could not find a published study that measures the full environmental footprint of an implantable system against disposable CGMs, though. The Eversense 365 still asks for fingerstick calibrations, a check of the sensor against a blood glucose meter: four at the start, one a day through day 13, then one a week [3]. Over a full year that is about 67 fingersticks by our count, each one using a test strip.

Material Trends and Future Directions

Manufacturers have been shrinking their sensors [1], but no all-in-one CGM we read about has dropped the single-use battery. Rechargeable designs do exist. MiniMed's 7-day Guardian 4 sensor still pairs with a separate Guardian 4 transmitter [6], and a 2024 review describes Guardian transmitters as charged about once a week and lasting up to a year [1]. The 2024 teardown authors point to less packaging, longer wear and reusable applicators as the biggest levers, since packaging and applicators made up most of the weight [2].

Regulation slows the redesign work. A 2025 commentary describes how revalidation, heavy documentation and a lack of regulatory precedent hold back recycled or biodegradable materials and packaging changes in medical devices [10]. People with diabetes want change, but it isn't what drives their choices. In a 2024 survey of 1,934 people with diabetes in Germany, Austria and Switzerland, 69% favored more reusable devices, yet environmental factors ranked far below safety and effectiveness when they picked a device [12].

Conclusion

Longer wear is the clearest lever we found. Moving from a 10-day to a 15-day sensor cuts the yearly count from about 37 to about 25 [5], and the Libre 2-to-Libre 3 redesign cut about 27 grams from the applicator that comes with each sensor [2]. Recycling is still unsolved: in the studies we read, used sensors went to incineration or household trash rather than metal recovery [1][2]. A 2026 review also notes that the actual environmental burden of diabetes care has not been assessed yet [11], so claims that any one system has the smallest footprint remain unproven. Which CGM fits you best is a decision to make with your care team, and waste is only one part of it.