Learning to Use My New MiniMed 530G with Enlite CGM system


It takes a while to make a change and learn something new.

Last spring I knew I was eligible, through my health insurance company, for an insulin pump upgrade after six years on the same one. I’ve been a loyal Medtronic user since 1993, so before making a decision, I compared the next generation Minimed with models by other makers and investigated continuous glucose monitors (CGMs).

Whether out of a comfort or a truly objective analysis, it’s hard to say, I stuck with Medtronic/MiniMed. One important factor, though, was a long talk with Carol, the Boston-area Medtronic rep, who demonstrated Minimed’s new system and showed me her own pump. Although I live in a big city and work for a university with 10,000+ employees, I do not know, in person, a woman with Type 1 diabetes. Carol couldn’t have known this, but our brief personal connection meant more to me than all the information that she and other manufacturer reps had provided. Here she was, representing lived experience.

Medtronic MiniMed 503G with Enlite CGM System
the MiniMed 503G with Enlite CGM arrives, in a bigger box

By the time I was ready to decide and place an order in November, the MiniMed 530G with Enlite CGM system was newly available. On the day it arrived in the mail, several boxes and folders inside one big box, I was excited. “My new pancreas is here!” I thought. Rationally, I knew that the integrated system was not passive: it still needed me and my brain in the control tower, so to speak. Yet how I felt is as though I were a pioneer, a first adopter of new developments in diabetes technology. I also believed (and still do) that I was re-committing to my own health and to taking advantage of resources that would help me manage my health well and for a long time.

The euphoria of beginning has faded, and I am still patiently climbing the learning curve.

The transition to the new pump came first. Before attending the classes at the Joslin Diabetes Center for the CGM, I wore the 530G for a few weeks. The insertion sets are the same, but the prompts in the user interface on the pump has been modified. For example, I no longer use the “Prime” function to change out an old reservoir and add a newly filled one (as I did with my old MiniMed pump), I use the “Reservoir + Set” function. There are other changes like this that make me stop for a few seconds and ask myself, “Is this what I want to do?” before proceeding. I am no longer on automatic.

The Enlite transmitter/sensor combo is itself diminutive in size, which made me anticipate that learning how to insert the sensor, connect it to the transmitter, and tape the whole thing down would be a breeze. It’s a different set of operations, with a different inserter, than the insulin infusion sets. I had to stop and think between steps. I also really needed Stacy, the nurse educator, and an instructional video and booklet to help me. Even though I’ve changed the sensor four or five times by now on my own, I need the booklet open in front of me to get the steps in the right order and with the right technique.

As an insulin pumper for more than 10 years, I have become speedy at changing out an old insulin reservoir and priming a new one; it takes me two minutes or even less if the needle goes into a soft spot on my flesh. The CGM set cannot be done in less than 20 minutes, if only because the transmitter needs to re-charge for that long before being initialized again. I only have to do this every six days (while I change the insulin reservoir set every three days), but there will be no rushing through this. I do it when there’s a pause in the day.

I’ve also made time in my life to learn this new technology. Joslin requires one initial and two follow-up appointments when learning the CGM. This training schedule was designed, Stacy told me, because they found at the Joslin that, if people had only one appointment, they would get frustrated with the CGM and give it up before really giving it a chance. When she told me this at my first appointment, I silently and smugly told myself that “I will be different,” but, guess what? I have been frustrated.

The new, unexpected challenge is coordinating my use of the blood glucose meter and the operation of the CGM, which does not measure blood glucose. It measures the glucose in interstitial fluid, and this is important to know because glucose levels in interstitial fluid lag about 30 minutes behind blood glucose. Only my blood glucose meter, which is part of the system, “knows” what my in-the-moment blood glucose is. And, furthermore, I need to make some decisions as to when I will use a blood glucose level as a calibration for the CGM. Two calibrations a day must be done; Joslin recommends two to four a day, with the ideal as four.

The best time to calibrate is when I know the level is pretty stable — that means early morning and end of day for me, and a couple of other times during the day when I haven’t just eaten or recovered from a hypoglycemic reaction. I’ve made some mistakes, and simply chosen “yes” when the meter, which wirelessly sends BG values to the pump, asks me if I want to use a blood glucose value as a calibration for the CGM. The result is that, instead of the BG meter and CGM getting in sync, the value might diverge by 100 points. Getting within 30 points of each other seems to be the goal.

What this has meant is that the CGM alerts have been waking me or interrupting me occasionally with flat-out incorrect numbers. It says I’m 243 when my BG meter says I’m a more reasonable 150. Conversely, it woke me once at night with a LOW BG alert of 69, and my meter check told me I was 120, which is also how my body felt.

There has been some benefits, though, on the learning path. It has woken me at night with its very insistent vibration to let me know my BG was a high 227. It was correct, and I would not have predicted this, having gone to bed at a smooth 111. (I blame it on a dinner that was high in both fat and fiber.) It has aroused me also with a LOW BG alert and been correct.

So far, the process has been equal in frustrations and benefits. I haven’t yet turned on the new functions of the pump/CGM combo, the prediction alerts or the threshold-suspend, which Medtronic claims is the first step to an artificial pancreas and closed-loop system. Those come next. I am intimidated by threshold-suspend (it’s optional), but the prediction alerts are a major part of why I chose the system and to “go CGM” at all.

There are many other things in my life I would rather be doing or other thoughts or problems I’d like to fill my head space with, other than learning how to use the pump/CGM system. Recently, I told the editors at Sanofi’s Discuss Diabetes that in the wake of my celiac disease diagnosis, I had to “make time for change,” to reconsider my diet, subtract old foods, and add new ones. It took both patience and clearing the day’s To Do list, to some degree. I am doing the same with the CGM, making time for change. I am still at the beginning; we have a ways to go.

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Kevin F
Kevin F
9 years ago

I agree with Steve, your frustrations are also the reason I went with Dexcom… and I couldn’t be happier. The G4 is “my best friend” as my fiance puts it- I rely on it so much that I feel lost when I’m not wearing it for whatever reason. I’m just so done with Medtronic- their pump really isn’t that great, the sensor still lags behind Dexcom, and quite frankly, I like having two devices. Trying to read the CGM on my pump when it’s on my belt is annoying, I’d rather pull the device out of my pocket, put it… Read more »

Michelle Page-Alswager

Thanks for the feedback, ok and Steve. I really like the MiniMed pump, so I will give the Enlite some more time and hope that my learning and the calibrations will converge. So far, though, the trade offs are many. I will report back after more time has gone by.

9 years ago

Your experience with the CGM from Minimed is exactly why I switched to Dexcom G4 Platinum. Even though the device is totally separate (meaning I have to carry another device) and has to be calibrated by a third device, it’s so much more accurate than the Enlite or even, I think, than the finger-sticks from Lifescan (the Dexcom will drift over a period of days, but it’s not nearly as noisy as the readings from my OneTouch). The technology is just better: it responds faster since it doesn’t average as many readings as the Enlite does, and it lasts longer,… Read more »

9 years ago

I was told that I would have to return the pump if I did not continue
with the CGM. In the past I gave up 2 companies CGM becasue the sensors did not  catch the lows accurately. They are geared for the higher end which
I don’t really need. Need for nights and when I go down low becasue of gastrpparesis.

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