Updated: Jul 16, 2020
by Bec Johnson
I have had type 1 diabetes for 19 years, and during that time, technology has changed considerably. When I was diagnosed, I was given long 12.7mm needles to inject my insulin with (ouch!) and I tested my sugar level with a blood glucose monitor that required finger pricks. Now, there are so many more options: I can choose to use an insulin pump or (much shorter) needles, and I can continue to prick my fingers or use sensors that monitor my glucose levels for me. As technology advances, diabetes becomes more and more expensive to manage, but it also makes life with diabetes safer and easier.
This month, I trialled the newest continuous glucose monitoring (CGM) system on the Australian market: the Dexcom G6. Here's my review:
Like most CGM systems, the G6 consists of a sensor that is inserted into the skin and a transmitter that is clipped onto the sensor. Glucose data are transmitted to a receiver, an insulin pump or to a smartphone. Unlike other CGMs on the market, the G6 requires no fingerstick calibrations. The sensors have a 10-day wear, are approved for people aged 2+, and Dexcom states that unlike other CGM systems, the G6 does not have issues with acetaminophen (paracetamol) interference causing false readings.
Insertion: The new applicator makes inserting the G6 a breeze. There are no plastic pieces to break away and no plunger system to push the introducer needle into the skin, like in previous systems. The new applicator has a housing to contain all the working parts, and a self-retracting needle - all I had to do was touch a button and I barely felt a thing. I think this will be terrific for anyone who cringes plunging the needle in with the current system like I do, and especially for young children.
Low profile transmitter: Clipping the transmitter onto the sensor, I noticed that the sensor and transmitter combo was slimmer and sat flatter than previous versions. Hopefully this will mean fewer sensors will be ripped off by catching on clothing and during sports!
No calibrations required: The other CGM systems on the market require calibration with blood glucose readings at multiple points throughout the day. This means stopping what you’re doing, testing your blood with fingerpricks, and entering the levels into the app that runs the CGM. Calibration alerts drive me nuts, and so having a system that required next to no calibrations and far fewer fingerpricks for a whole ten days was terrific. You can still calibrate if you really need to - I did have to calibrate once, when the sensor gave me a false low alert during the night, to get the system back on track.
Customisable alerts and interoperability: The G6 has customisable alerts for different times and days – you can set it on silent for a day of meetings, and on a loud alert to wake you as soon as your glucose level moves in the wrong direction at night. You can also send glucose data to a receiver, smartphone or insulin pump (the Tandem T:slim).
The algorithm: This is the part that really matters. The G6 runs on a new algorithm that is claimed to have improved accuracy and a reduced lag time between the sensor level and a blood glucose level compared with previous models – indeed, this paper found the lag time between lab-measured blood glucose and G6 sensor glucose averaged only 4 minutes, with 23% of study participants experiencing <1 min lag time. I did multiple tests to compare the G6 and my blood glucose meter. There were some discrepancies (up to 2mmol/L) in the first 24 hours, but given the G6 is the first CGM to have passed more stringent rules from the US FDA around CGM accuracy (based upon the percentage of sensor readings that were within 20% and 15% of lab-tested blood glucose readings) that my blood glucose meter might not have tested as well on - it might well have been my blood glucose monitor that was the problem. All up, the G6 gave me readings I felt I could trust to dose insulin from.
Ten-day wear: Diabetes means a life of constantly remembering - remembering to test, to take insulin, to change sensors and pump sites. Normally, CGM sensors have a seven day use, and it was nice to get an extra three days’ grace from the G6.
The price: If you aren’t eligible for the government subsidy for people with concessional status, under the age of 21 or pregnant women, sensors for the G6 cost $330 for a box of three, which gives you one month of continuous CGM. You’ll also need to buy new transmitters four times a year, which cost $400 each. These are prices for standalone purchases - the supplier, AMSL Diabetes, has brought out a subscription price that is lower if you sign up for 12 months’ supply. Check the AMSL Diabetes website or call AMSL Diabetes for more.
G6 sensors can’t be restarted easily: Dexcom sensors from previous generations (eg the G5) last for seven days before they are factory set to switch off. Although it’s not recommended by the company, many people extend their sensor life by restarting their sensors, getting another week or two of life out them and reducing their costs considerably. The G6 was approved on the basis that it cannot be restarted, because accuracy can’t be guaranteed beyond a ten-day wear. However, (although I didn’t try it) it appears that members of the diabetes community have figured out how to restart the G6, too - although the process appears to be quite a bit more onerous than with previous models.
Slow connection time: I found that when the system lost signal, it took a while to reconnect. The time taken to reconnect was problematic for me at swimming training, where in order to check my level, I’d wait at the end of the lane for the sensor to connect back up with the receiver, which I kept close by in a waterproof bag on the pool deck. Most of the time - even when my coach took his time to explain a long and complicated set - the receiver hadn’t picked up the signal by the time I needed to set off swimming again, so I had to train without knowing my glucose levels.
The applicator: The applicator is quite bulky, and would take up a lot of room in a suitcase or your diabetes drawer. Sadly, the applicator is single-use; I didn’t like having to throw away such a large piece of plastic after I’d inserted the sensor.
While I think G6 will be an awesome tool for most people, I’m not going to become a full-time user for two reasons. The first is very specific to my life: Bluetooth doesn’t work in water and so with all CGM systems I can’t easily measure my levels when I most need to - at swimming training. The second: (I'm sure many others will also identify with this) like most people with type 1 over the age of 21 in Australia I am not eligible for subsidised CGM, and its cost - which runs into the thousands each year - is a major barrier to use for me.
That said, I enjoyed my trial of the G6, especially feeling that I could trust it to be accurate enough to dose insulin from without calibrations, which is the key feature that sets it apart from other systems on the market. I like seeing my data in the kind of detail the system offered me, I liked the customisable alerts and the pain-free insertion, and I learned a lot from the comprehensive report about my glucose levels from Dexcom Clarity afterwards.