The Ergohacks Verdict

One of the big potholes we hit after our daughter was diagnosed with Type 1 Diabetes 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. 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 system had a significant impact straight away. She experienced less frequent lows and with insulin suspending half an hour beforehand, episodes of hypoglycemia was less severe. Managing her diabetes became much easier as we knew not only what her levels are, but how they were changing. It also felt like less of a full-time onslaught. There’s no need to wonder and worry like we did with just finger pricking, there was no need to constantly check and evaluate like we had to do with the Libre, we could forget about it until her pump alarm sounded.

It isn’t a perfect system though. We had some accuracy issues with fairly large discrepancies between blood glucose readings and sensor readings, particularly first thing in the morning. It was much more accurate than the Libre, but not so accurate that we could make significant decisions without confirming its results first with a finger prick test. Additionally, we started having more problems from early April 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 just 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 were failing 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 wouldn’t arrive.

Towards the end of June 2017, things improved. Sensor accuracy returned to former standards of in the ball park, dropouts were down to a few times a day lasting less than 30 minutes each time and premature failure became a thing of the past. Customer support returned to being excellent. Back-logged replacement sensors arrived. Two significant problems remained: Access to 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 so we have no access outside of her pump to CGM data. Second – it’s become hard to get a hold of sensors with significant shipping delays, leaving us worried that we’ll run out.

Despite the system’s few imperfections, Enlite sensors are 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 made it easier, more predictable and safer. Recommended to those with a Medtronic 640g pump who experience significant problems with hypoglycemia. It’s strongest selling point is its SmartGuard feature that most definitely made a huge difference to the severity of episodes and gave us great peace of mind, particularly at night.

Ergohacks Essential

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 for most the only option (even if your insulin pump is via the NHS).


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 painful to insert, they drop out just when you need them most and they stop sticking well around day 5 when immersed in water a lot. I give it four 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 activates 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.


* Compatible Medtronic insulin pump
* Some technical expertise

ergonomicinclusivedesignBuild quality

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.

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 September 2017.