The Next Big Thing – Medtronic Diabetes 670g Hybrid Closed-Loop System
By Allen Lightcap
This Halloween, I will be commemorating my 27th year since being diagnosed with Type 1 Diabetes. I am now 38 years old and until recently had never imagined what it might be like to live without diabetes, or to get some relief from this relentless disease.
I have run the gamut of available therapies with mixed results – multiple daily injections of a long lasting insulin coupled with a short term insulin for meals was the only option I had heard of until I was introduced to insulin pump therapy in 1999. There was a lot of freedom gained simply moving from injections to the pump, and improved control in my A1C. From there, I continued upgrading to the latest and greatest insulin pump and then introduced a continuous glucose monitoring system 4 years ago.
Being able to monitor in relatively real time what my blood sugar was, watch it trend upwards or downwards, and receive alerts in advance of these adverse trends was another step in freedom from the daily grind. But even with the best in insulin pump therapy and CGMS, I was still relegated to helplessly watching the trends after I had made a “bad” decision – either a few slices of pizza which was pushing my sugar up, or an unplanned bike ride with my kids that was now dragging my sugar down. Why should an attempt at a normal life be a “bad” decision?
I’m sure most, if not all, Type 1 Diabetics have felt this helplessness from time to time.
There have been days on end for me for which I could not get my glucose to come down to a normal range, and many a day that no matter how much I ate I could not keep it above 80 mg/dl for any length of time. With all the evolutionary changes to my diabetes therapy, I was still required to tweak my basal levels and decide on a regular basis how much this meal, or that exercise, would impact my blood sugar. And God forbid I get it wrong – then I would need to readjust and think about how to modify with an additional bolus, or extend my temporary basal level.
Recently, Medtronic Diabetes introduced their 670G insulin pump, which they hailed as the first “hybrid closed-loop system.”
It is the first commercially available system in the United States to use CGMS data to automatically adjust the basal levels delivered to the patient. I had upgraded to their 630G system at the end of 2016 and was a candidate for their rollout of this new approach, and because I generally like to upgrade my insulin pump (and iPhone) when a new one is available, I signed up.
To be perfectly honest, I didn’t expect much to change with my control or my life with a system taking over just the basal rates, but I viewed it as the next evolution in insulin pumps – eventually moving to a fully closed loop system which would also calculate meal time boluses and include onboard glucagon (aka artificial pancreas).
Attending the training classes, I had many questions about how the pump would account for the things that tripped me up the most, like the pizza or bike rides. I had been in control of my insulin pump for 18 years, adjusting those basal rates like a boss, and no microprocessor was going to effectively take that away from me. Giving up that control and letting the system do its thing was one of the most difficult transitions, as visions of bottoming out in the middle of the night, or in the middle of an important meeting, danced in my head.
In my 2 weeks on the new system, I noticed an immediate change in the amount of time I spent above 180 mg/dl, the high limit of my normal range.
My diabetes educator sat down with me for my first review, and I was surprised to see the stark difference in glucose trends. Prior to starting on the 670G system, I was only spending about 34% of my time in a target range of 80-180, with the remainder of that time generally spent suffering through or recovering from a post meal spike up to 250 or 300. I had learned to cope with this fatigued, nauseous feeling and my A1C was not in a terrible range, and I would rather have a higher post meal spike than to deal with a low.
My first 2 weeks on the Medtronic Diabetes 670G system I had more than doubled my time in range to 74%, and I could really feel a noticeable difference.
No longer was I plagued with the chronic fatigue that accompanies those high blood sugars. I didn’t worry about a low blood sugar because the system will react (to a point) to your sugars trending downward and will reduce the basal insulin delivered. And the biggest difference for me was the aggressiveness with which I approached my meal time boluses. I had been living in fear of a low, and would consistently under bolus, causing the continual spikes and corrective boluses to get back into range. I now approach my meals much more realistically and find that I am now appropriately bolusing, knowing that if I miss the mark a bit the system will adjust.
What it won’t do is pick up all the slack if you under bolus or miss a bolus entirely, or if you take way too much. Those dangers are still real.
The Medtronic Diabetes pump is continuously adjusting my basal rate to target a glucose of 120 mg/dl, but will only adjust so far. It also allows me to input a temporary target of 150 if I am going to be doing some strenuous activity. But leveraging this new system has given me a tremendously increased sense of freedom to live my life on my terms, pizza and bike rides included.
Ironically, giving up control to the machines has actually made me feel more in control of my diabetes than I have felt in the preceding 27 years. Is the system perfect? No. I still have to do many of the same things I have had to do for years, such as calibrating a sensor, changing an insertion site, and dealing with the occasional high or low blood sugar. But the highs and lows are less frequent, and more manageable. And they are generally explainable as “whoops” moments where I didn’t properly perform the carb counting guessing game in my head.
What has dramatically improved is a reduction in the unexplainable hours or days with a high or low trend that I can’t do enough to correct.
The flexibility to start working on a home improvement project or hike without adjusting my basal, worrying if the adjustment is enough or too much. Overcoming my own personal fear of bolusing too much, choosing the lesser of two evils and opting to under bolus and correct later.
These are the incremental improvements in the quality of life I have already experienced. And I am excited for what the next evolution in insulin pump therapy holds.
So much has been promised with a T1D “cure” – a truly closed loop insulin pump/CGMS system, islet cell transplant/implantation, etc. But for now, I am extremely grateful for the freedom this new system brings, and future innovations on the horizon.
Learn more about the world’s first hybrid closed loop system by Medtronic Diabetes.
Have you tried the new Medtronic Diabetes 670g system? If so, leave your opinions below.