Type 1 Diabetes management is an all-the-time thing, every minute of each day. The body no longer produces (enough) insulin and so a highly complicated automated physical function now has to be done manually. One of the big potholes we hit after our daughter was diagnosed and was set-up with an insulin pump, was not knowing what her glucose levels were most of the time and thus being unable to help her artificially raise or lower them.

We experimented with Abbot’s Freestyle Libre flash glucose monitor, but hit two problems it could not overcome: (i) we couldn’t calibrate it, which reduced its accuracy and reliability and (ii) it’s a passive system. Our daughter struggles with nocturnal hypoglycemia and we wouldn’t know she was low unless we happen to be scanning with the Libre sensor at that moment. Her levels have dropped so low that we had difficulty waking her and when we finally managed it, she was highly resistant to treatment.

Medtronic’s CGM system offered the solution – it can be calibrated and it’s integrated with her Medtronic insulin pump. It continuously monitors her glucose levels with updates every 5 minutes and has customizable built-in alarms. It even goes one step further – suspending insulin basal delivery when low or when approaching low to prevent hypoglycemia.

The Ergohacks Verdict

Diabetes management is complex, time consuming and difficult. Every extra piece of technology we’ve picked up along the way has made a significant improvement, but Medtronic’s CGM system has by far made the most significant impact on her life quality, our stress levels and our joint competency in managing her day-to-day glucose levels.

The SmartGuard basal suspend has made a notable difference in the frequency and severity of lows and in combination with conservative alarms, makes it easy to quickly react to rising or falling levels before they become problematic. Management is much easier when we know not only what her levels are, but how they are changing and how fast. There’s no need to wonder and worry like we did with just finger pricking, there’s no need to constantly check and evaluate, like we had to do with the Libre, we can forget about it when we want to until her pump alarm sounds.

We had some problems from early April to mid-June 2017 with sensors not lasting the full 6 days, highly incorrect readings, sensors that just didn’t pick up changes in levels, dropped out frequently and simply failed instantly after a single rapid rise in glucose levels, one sensor never worked straight out of the box. Customer support wasn’t great either, simply confirming that sensors did fail prematurely and informing us that the only option was to change it out for a new one. Some sensor refunds were promised, but sensors were in short supply and replacement sensors were not sent out.

For the last fortnight, things have drastically improved. Sensor accuracy for the last 2 consecutive sensors has been highly accurate again with less dropouts and no premature failure so far. Customer support has been excellent, back-logged replacement sensors has arrived and although there are still some problems, it’s the usual small things. The system has never been perfect. The sensor regularly drops out for a few minutes, sometimes longer for no obvious reason. It doesn’t work in places with lots of bluetooth devices – like Southampton’s Ikea – and although the sensors are highly accurate the vast majority of the time – it isn’t all the time.

CGM results are not actionable – before treating lows or bolusing insulin, a finger prick test is needed to confirm its values. In addition, CareLink™ Personal, Medtronic’s proprietary software application used to download the data from the pump, is antiquated and no longer works on a Mac or the latest version of browsers. Medtronic recommends not installing software patches – including security patches – an unsustainable solution. We hope that a new system will take its place in the near future, but there’s been no news on any developments. However, despite the system’s few imperfections, it’s on the cutting edge of Diabetes technology, made to a high standard by one of the world’s leading companies in diabetes care and supported by a robust 24-hour helpline. Living with Type 1 Diabetes (and being the parent of a child with Type 1 Diabetes) is a time-consuming, stressful, unrelenting roller coaster, but Medtronic’s CGM system has made it easier, more predictable and safer. Recommended.

Retailer: Medtronic +                   

Price: ±£490 Starter pack (1 month supply). After that £55 per sensor (lasts 6 days). A Guardian Link Transmitter is £490.

Discount: Medtronic’s CGM is rarely available through the NHS and only in exceptional circumstances. Self-funding is an option (even if your insulin pump is via the NHS), however Medtronic doesn’t seem to offer their loyalty scheme at this time and currently no discounts on sensors are available.

About Medtronic

Medtronic is a global company founded in 1949 and headquartered in Dublin, Ireland and Minnesota in the US. They are the world’s largest medical technology developer and employ almost 100,000 people. They are at the forefront of diabetic equipment research as well as spinal, cardiac and neuromodulation devices.


This CGM system requires three components: (i) A compatible Medtronic insulin pump (640G in the UK, 630G in the US), (ii) Enlite sensors (each sensor lasts 6 days each and are not reusable) and (iii) one Guardian Link Transmitter that attaches to the sensor. The complete package really has three primary functions:

Continuous glucose monitoring

CGMs are increasing both in use and popularity. It’s difficult to control your glucose levels when you don’t know what they are at a given point in time. Finger prick tests only give one number at one point of time – it doesn’t tell you if its going up or down, how fast it’s changing or how long it’s been at the level it’s at. Flash monitor systems, like the Libre, only give you a number when you scan it – it doesn’t alert or alarm.

CGMs on the other hand, automatically checks interstitial glucose levels every 5 minutes and display them. They have alarms that can be set to alert the user to significant data and when levels are in range and stable, there’s no need to even think about the numbers, but if you’re curious, the data is always there. Knowing what your blood glucose levels are and will probably be doing over the next hour, is a vital step in controlling them.

The extra data is very useful. We can spot trends, check insulin levels and correct bad habits. It’s much easier to check and correct basal rates, carb and correction factors. She feels safer and more confident with it, happier to venture a bit further without a parent nearby to step in because life is simpler because of it. She gives it four stars out of five because the sensors only last six days, (she’d like them to last a year), they’re a bit painful to insert and they stop sticking well around day 5 when immersed in water a lot. I give it five out of five stars because, as a parent, I feel that’s a small price to pay for the safety net it provides.

Customizable alarms

It sounds like a little thing, but having the option to set your own alarms is a huge benefit. High limits can be set from 5.6 to 22.2 mmol/L whilst low limits can be set from 2.8 to 5.0 mmol/L. There’s the option to alert on high/low as well as before high/low. For low values, it’ll alert 30 minutes prior whilst for highs it can be set for 5 – 30 minutes prior. You can set up to 8 different settings over a 24 hour period. A customizable snooze for high/low alerts is also available.

For those who detest alarms, the ranges can be set wide to only alert the user to potentially serious excursions, whilst for those after tight control, alarms can be set to alert the user up to 30 minutes prior to glucose levels stepping out of range. Alarms are vibrate, audio or both and can also be temporarily silenced with a global setting (except for the low alarm) when you don’t want them – such as during an important meeting.

A note on repeated alarms
Be aware that when the high or low alarm sounds a second time, it doesn’t mean levels are still rising or falling, it just means that the new value is still outside of the set target range. For example: if your SG(sensor glucose) is 3.2 and then fifteen minutes it’s 3.7 and your low level is set at 4.0, it will sound the low alert both times.


The Smart Guard feature is one of the Minimed system’s appeals. It allows the pump to automatically suspend insulin delivery either on low or before low and then will automatically resume insulin delivery when levels rise. As stated above, the low limit can be set between 2.8 and 5.6 mmol/L. If  “Suspend on low” is selected, insulin delivery will automatically stop when the limit is reached. If “Suspend before low” is selected, insulin delivery will automatically stop if levels are predicted to reach the target low in the next 30 minutes.

Insulin delivery will be resumed afterwards when two conditions are met: (i) insulin level reaches a number 1.1 mmol/L above the set low and (ii) insulin levels will reach at least 2.2 mmol/L above the target low in the next 30 minutes. Insulin delivery will always resume after 2 hours though, whether the above conditions have been met or not. SmartGuard is unavailable for 30 minutes after insulin is resumed (either by user or pump), but if the user is unresponsive to the SmartGuard feature for more than 30 minutes after resumption, it will be unavailable for the next 4 hours.

It’s not a perfect solution to hypoglycemia – if glucose levels are rapidly dropping, suspending basal insulin won’t be enough to prevent hypoglycemia. Suspending basal insulin offers no guarantee that glucose levels will spontaneously recover – testing and treating hypoglycemia remains vital. If the SmartGuard feature activates multiple times a day – it can really mess up basal delivery, but conversely, that’s also an excellent indicator that basal insulin rates are not appropriate.

We’ve experimented with the feature – using suspend on low and suspend before low as well as setting the low threshold anywhere between 3.2 and 4.8. After ten weeks of use, we’ve mainly settled on suspend before low whilst setting the low figure at 3.6. It means that insulin tends to suspend when glucose levels reach the 4s and are dropping steadily or it actives in the 5s when levels are rapidly dropping. The great advantage is in the resume which happens at 4.7ish when levels are set to reach 5.8 within half an hour, which for us avoids a second low as well as any spikes.


  • Continuous glucose monitoring
  • Customizable alarms
  • SmartGuard
  • Data compatible with Nightscout



* Compatible Medtronic insulin pump
* Some technical expertise

ergonomicinclusivedesignBuild quality

We based our Ergohacks Verdict on 5 months of using the Enlite Sensors paired with a Medtronic 640g insulin pump. This article was first published on 21 March 2017 and last updated on 2 July 2017.