Power Management and Miniaturization in CGMs

Power Management and Miniaturization in Continuous [Glucose Monitoring](/) (CGMs)

Introduction

A continuous glucose monitor (CGM) is a small sensor worn on the body that measures glucose in the fluid under the skin and sends a reading to a phone or receiver every few minutes. The Dexcom G7, for example, reports a new value every 5 minutes for up to 10 days [3]. Each of those transmissions draws on a battery small enough to sit on your arm. That's why power and size are really one engineering problem: a smaller device leaves less room for a battery, so the electronics have to spend every bit of energy carefully.

Innovations in Power Management

The biggest power saver in current CGMs is the radio. Sensors send their data over Bluetooth Low Energy (BLE), a low-power form of Bluetooth; the FDA's review of the Dexcom G6 describes the system as a sensor, a BLE transmitter and a BLE-enabled display device [1]. Here's what surprised us: with a radio that frugal, the G6's clip-on transmitter was built to be reused for up to three months, and the FDA review found its battery had enough life to work for that long [1].

Researchers are also studying energy harvesting, which means collecting power from the body itself (body heat or motion) or from outside sources like light and radio waves [2]. It hasn't displaced the battery yet. A 2020 review of power sources for body-worn sensors called batteries the most mature option and the one most widely used, while noting that their energy density has improved only slowly [2].

Miniaturization of CGMs

Most of the recent size savings came from merging two parts into one. The Dexcom G6 paired each 10-day sensor with a separate transmitter that was reused for 90 days; the G7 that followed builds the transmitter into a single-use unit with a useful life of about 10.5 days [3]. Dexcom lists the G7 sensor at 1.07 by 0.94 inches, and calls it an all-in-one sensor and transmitter [6]. That design changes the power math, because the battery only has to last one wear instead of three months.

MiniMed, the name Medtronic MiniMed, Inc. now sells its diabetes devices under, made a similar shift. Its Simplera, Simplera Sync and Instinct sensors are all-in-one, while the Guardian 4 sensor still connects to a separate Guardian 4 transmitter [10]. Engineers also credit microelectromechanical systems (MEMS), which are tiny mechanical and electronic parts made with chip-manufacturing methods, and nanotechnology for shrinking sensors and electronics.

Patents and Manufacturers

Several companies hold patents related to power management and miniaturization in CGMs. Dexcom holds patents for low-power sensor designs and energy-efficient data transmission methods [4]. Medtronic, whose diabetes devices are now sold under the MiniMed name [10], has patents covering miniaturized sensor technologies and power management systems [5]. Keep in mind that a patent records what a company claimed to invent. It doesn't tell you which of those ideas ended up inside a product you can buy.

Latest Product Lines and Comparison

As of October 2026, Dexcom's current prescription sensors are the Dexcom G7, worn for 10 days, and the Dexcom G7 15 Day [6]. The G6 is on its way out: Dexcom says it will no longer manufacture the Dexcom G6 after July 1, 2026, though pharmacies may have supplies for a while [8]. The G7 is smaller than the G6, but its battery does not last longer. The G6 transmitter was reusable for 90 days, while the G7's built-in transmitter is single-use and lasts one wear of about 10.5 days [3].

Abbott's current FreeStyle Libre sensors are the FreeStyle Libre 3 Plus and FreeStyle Libre 2 Plus, both worn for up to 15 days [11]. The earlier Libre 2 and Libre 3 sensors (without "Plus") were available only through September 30, 2025 [11]. Abbott describes the Libre 3 Plus as the world's smallest 15-day real-time CGM sensor, a claim it bases on its own data on file [9].

MiniMed's current sensors are the Instinct sensor (15 days), Simplera Sync and the standalone Simplera CGM (each up to 6 days, plus a 24-hour grace period) and Guardian 4 (up to 7 days) [10]. Guardian Connect, a standalone Medtronic CGM the FDA approved in March 2018, has been superseded and is no longer among those sensors [10] [12]. Its transmitter powered the Guardian Sensor (3) and sent data over Bluetooth to a phone app [12]. Switching to a newer sensor takes a new prescription [8] [11], so it's a conversation to have with your care team.

Pitfalls, Warnings, and Issues

Low-power radios share crowded airwaves. The G6 was tested against common household devices in the same 2.4 GHz band it uses, and the FDA found it tolerated that interference and still met its performance targets; 98.6% of expected readings were received over the sensor's life [1]. FDA guidance explains why that testing matters: devices in this band aren't entitled to interference protection, and other transmitters nearby can cause data errors or lost data [7]. The same guidance asks makers to keep radio output at the lowest power that still works reliably [7], which happens to suit a small battery too.

You may read that power-saving measures can compromise sensor accuracy. We could not confirm that in FDA records or manufacturer labeling, so treat it as unproven. Cost and access remain real concerns for many users of these devices.

Conclusion

In the products we reviewed, the direction is consistent: long-lived reusable transmitters are giving way to small, all-in-one sensors whose batteries only need to last a single wear [3] [10]. What's still unknown is whether energy harvesting will ever be practical in a body-worn CGM. The 2020 review we read still treated batteries as the most mature power source [2].