What powers the Dexcom transmitter?

When I was on the Minimed CGMS, the transmitter came with a small charger and one needed to charge the transmitter every 10 days or so. I switched to the Dexcom 7+ recently and didn’t even realize that there is no such charger for the transmitter in the starter pack that I received. I looked over the user manual and there is no mention about the power requirements or charging for the transmitter. Am I missing something?

The sensor and transmitter are one part for the Dexcom. You get a new transmitter everytime you put on a new patch. So you’ll never have to worry about getting a new transmitter when it won’t charge anymore, b/c you get a new transmitter everytime you put on a sensor.

The transmitter is powered by Silver Oxide Batteries.

This is an excerpt from the 7+ User’s Guide:

The Transmitter wirelessly sends your glucose information from the Sensor to
the Receiver. Once you insert the Sensor, you will snap the Transmitter into the
Sensor Pod using the Transmitter Latch. The same Transmitter is used when
you change Sensors.
As the Transmitter nears the end of its battery life, it can sometimes lose
communication with the Receiver. This can happen even if the Receiver and
Transmitter are within 5 feet (1.5 m) of each other. Once the Transmitter battery
has drained, you will need to replace the Transmitter because it can no longer
communicate (talk) to the Receiver. You can easily set up a new Transmitter
to talk with your RecTransmitter ID”).

Dexcom is unique in how they measure glucose in interstitial fluid (ISF).

On another forum, MM users say that their transmitter and receiver communicate every 10 seconds, which is why the transmitter must be recharged at least weekly. I am pretty sure the Navigator works the same since they must also re-charge.

The Dexcom transmitter only sends data twice in a 5 minute period and at a lower frequency than MM and Navigator. Dexcom had to apply to the FCC to be exempted from the MICS (Medical Implant Communication Standard) and this allows them to transmit at 402 - 405MHz. The combination of the lesser number of transmissions and the lower energy frequency allow the Dexcom transmitter to last for up to 18 months on a single battery, with no need for recharging.

Another plus to this approach is since the Dexcom transmitter does not need to be recharged, it securely fits into the sensor without any need for taping it down, since there is no need to remove and re-charge it. Dexcom supplies a special tool to remove the transmitter from the sensor. I have read where MM users tape their transmitters down to make sure they do not lose it. MM has to make the transmitter easy to remove for re-charging purposes, but some users fear that it may accidentally dislodge.

The downside of the Dexcom approach is if the transmitter and receiver lose contact, it will take a longer time to re-establish the connection between the two since the Dexcom only will try to do so twice in a 5 minute period. Both MM and Navigator will re-establish connections faster since they communicate more frequently. The Dexcom lower power transmissions also limit its range to 5 feet, whereas both MM and Navigator have more range.

So the trade off is, do you want more range and faster reconnects at the price of having to recharge the transmitter or can you live with the 5 foot range and the slower reconnects of the Dexcom.

Excellent post! thanks, Ricardo.

I have used both the MM and the Dexcom. The range of transmission was so small that I could not have the pump and the sensor on opposite sides of my body. They had to be closer. The Dexcom does not seem to be quite so limiting. I have the sensor up high on on my abdomen and the receiver in a bag around my waist at night, which I rotate as I turn in my sleep, and it never lost contact.