At the 2014 ADA Scientific Sessions, there were several reports on progress on artificial pancreas (sometimes called "closed loop"). Unfortunately, all of them were reported on a day that I was not at the convention, so the information below is mostly from the printed materials at the convention, news reports, and convention "buzz".
The "Bionic" Pancreas:
Bihormonal, Closed Loop, Artificial Pancreas Progress
This was clearly the big news of the scientific meeting. Here is my previous coverage on this (and it includes links to DiaTribe's more complete coverage):
Bihormal refers to supplying both insulin and glucagon (so it can raise or lower a person's blood glucose). Closed loop artificial pancreas refers to automatic dosing as needed with data from a CGM to a pump without human intervention. Bionic is a marketing name used by Dr. Damiano's group at Boston University.
There were two big publications on the Bionic AP. The first was in a scientific journal, published the month before the show, and the second was a presentation at the show.
First, I'l discuss the study published just before the show. The basic set up was that people wore the devices for one day of calibration, and then two days of data collection. Data was collected for four groups: adults and adolescents, and people who signaled when they were going to eat a meal, and those that didn't. No one counted carbs or dosed in response to meals. The signaling group just told the AP that they were about to eat a breakfast, lunch or dinner; nothing about the content.
| Group |
Average BG
|
Estimated A1c
|
% in range
(70-180)
|
| Adults Before Treatment | | 7.3 | |
| Adults who signaled meals | 132 | 6.2 | 80 |
| Adults without meal signaling | 142 | 6.7 | 70 |
| Adolescents Before Treatment | | 7.9 | |
| Adolescents who signaled meals | 162 | 7.3 | 68 |
| Adolescents without meal signaling | 175 | 7.7 | 60 |
What this means, is that for adults who did not signal when they were going to eat, they had an average BG level of 142, a likely A1c level of 6.7 (if they had done this for 3 months), and their BG levels were in range 70% of the time! Now, that looks pretty good, but the news gets better.
Here are the results from the follow up study, done by the same researchers, and given as a scientific talk. This study was "free range" adults who were free to roam over 3 square miles of Boston, staying in a hotel, working out at a gym, and eating mostly at restaurants, while the adolescents were attending camp. For this study, no one signaled meals. It included 20 adults and 32 adolescents, which makes it phase-II sized by my reckoning.
This study has only two data points that matter:
Average BG Number
(for both adults and adolescents)
|
Estimated A1c
|
138
|
6.4
|
There was slight complexity in the data. That 138 number was the average over all five days of the test. The researchers expected that the first day would be worse than the other four, because the unit was calibrating itself to the patient the most during that first day. For adults, this worked out, the next four days average BG was 133 suggesting that long term use would result in an even lower number, and might even drop a few more points (over time, as the AP better learned how the person reacted to insulin, glucagon, and food). But for adolescents, that's not what happened. They averaged 147 over days 2-5. Even if 147 (A1c of 6.7) is the long term number, that is still a complete success. It is lower than the ADA standard of 7.5 for adolescents. But it is a mystery to me why those days should average higher than the first day.
Summary of NEJM data:
http://www.nejm.org/action/showImage?doi=10.1056%2FNEJMoa1314474&iid=t02
Note: information for this section came from an ADA abstract, a JCEM paper, and a NEJM abstract. You can read the whole NEJM article here:
http://www.nejm.org/doi/full/10.1056/NEJMoa1314474#t=articleTop
JCEM abstract here:
http://www.ncbi.nlm.nih.gov/pubmed/24483160
Single Hormone vs Bihormonal Artificial Pancreas
A group from Canada gave a talk where they directly compared injected insulin, an insulin AP, and an insulin and glucagon AP. For average BG numbers, they found that both types of APs were similar to each other (the dual pumps were only very slightly better), and that they were both significantly better than injections. However, when they looked at low BG events, then the dual hormone APs had significantly fewer such events than single hormone APs. This makes sense, since the dual hormone pumps can directly prevent lows by dosing glucagon.
So this Canadian trial suggests that a bihormonal AP might do a little better than a "classic" AP, but it should not do vastly better, if measured by average BG. When I first saw that poster, I was a little dubious. Two hormones seemed like much better technology than one. But then I saw the results below. One of the complexities, is how does one measure an AP? Using average BG is easy and straightforward, but should we also measure low BG events and/or high BG events? If you do (especially low BG events), then the dual hormone APs might look better in comparison.
The Cambridge Artificial Pancreas
With all the excitement about the bihormonal AP, it is important to remember that there are also several "classic" AP projects out there. For example, the results from the Cambridge AP, a "classic" insulin-only AP, were almost as good as the bihormonal results. There were something like 7 presentations on various aspects of this project, so it was very well represented.
The "24 hours a day" trial included 17 people, and ran for 16 days (8 days with AP and 8 days with regular treatment). They also reported on a nighttime only trial, which ran for 90 days! Again, half with AP and half with regular treatment.
It's big results that matter, from the 24 hour and day trial, are:
Average BG Number
(for both adults and adolescents)
|
Estimated A1c
|
146
|
6.7
|
MD-Logic Artificial Pancreas Project
What's better than two closed loop, artificial pancreas projects? Three! The MD-Logic project uses a "fuzzy logic theory algorithm" to predict insulin dosing. The research group presented a poster, which showed that using the MD-Logic AP at night, improved BG numbers the next day. This clinical trial included 24 people and lasted for 3 months (6 weeks using the AP, 6 weeks not, for comparison).
People who used the AP woke up about 15 points lower (on average) than people who did not use it. Looking at all the BG numbers the next day, people who used the AP the night before had an improvement of about 11 points on average. People who did not use the AP were in range about 66% of the time, while those not using the AP were in range about 62% of the time. (Range was 70-180).
Source is poster 949-P.
The Virginia Artificial Pancreas
This is another ongoing research project into a "classic" artificial pancreas. In the trial reported on at ADA 2014, 13 people were tested for 42 hours: 14 hours "open loop" treatment, and 28 hours of "closed loop" treatment. People in the trial could move about a hotel. This same research group is planning a 2 month trial of the same AP.
Source is poster 954-P and 104-LB.
Direct Comparison
| Group |
Average BG
Estimated A1c
|
Size
|
Adolescents?
| Duration |
AP Use
|
| Boston University | 138
6.4 |
53
| Yes | 5 days | 24 Hours/Day |
| Cambridge |
146
6.7
|
17
|
No
| 8 days | 24 Hours/Day |
| MD-Logic |
|
24
|
Yes
|
90 days
|
Night Only
|
| Virginia |
135?
|
13
|
No
|
2 days
|
24 Hours/Day
|
When you look at that, you might say the two hormones are better than one. But I would not read too much into that difference. It's not huge (8 BG points and 0.3 A1c), and remember that the single hormone solution is simpler all the way around: only one hormone to buy and load into the pump, less moving parts on the device, and so on. (Not to mention the fact that Glucagon hasn't yet been approved for this application, although that is expected.) Of course, the comparison is based on average BG, so might miss extra low BG events in the single hormone APs.
None of this competition bothers me in the least. I love the idea of having four closed loop systems getting to market at about the same time with slightly different feature sets. Having a bihormonal AP with slightly better control competing against a single hormone AP which is slightly simpler, sounds like just the sort of competitive situation that feeds progress in a capitalist economy.
Other Bits and Pieces
Poster 75-LB compared CGM data from actual BG data (measured using laboratory grade equipment) from blood pulled directly from a vein. They found that CGM data was very similar to the actual BG data, and that even when different, the differences were small. The researchers conclude that existing CGM technology is not the "weakest link" of AP technology.
Poster 747-P asked people who were testing a closed loop AP, what they thought of it. They liked it. They liked it because it provided better BG control, reassured them that nothing bad would happen while they slept, and improved BG control the next day. Poster 110-LB contained similar information, but focused on the remote monitoring of an AP in a family situation (ie. parents remotely monitoring children). A major conclusion of this research was that families wanted the AP/remote monitoring combo being tested; it did not need any improvements at all, it just needed to be made available.
Poster 948-P tested a closed loop system using diluted insulin compared to regular insulin, for small children (aged 4-7). They found that diluted insulin worked a little better. Average BG levels were the same, but time spent in range was 8% higher when diluted insulin was used.
Poster 951-P tested a closed loop system which (in addition to BG data) also used energy expenditure and galvanic skin response data. These are two measures of energy use. The hope was that by using energy expenditure data, they could make a better AP. However, the data showed very little difference between using this data and not, and even this little difference was only when BG was above 250.
Summary
My summary of closed loop, artificial pancreas research is this: We are seeing cure level control in phase-II clinical trials and for several different AP systems. This is great news, for several reasons. First, it means they "only" need to get through phase-III trials (and marketing approval) for these APs to be sold in the US. They don't need to do better than the results they already have, just produce the same results in larger trials. Second, it means that if one falls apart, there are others which can still get marketed. Third, it means that the technology is ready. When one AP is successful, that team might just be ahead of the rest, but if four groups can do it, that means the technology is here for all.
Joshua Levy
http://cureresearch4type1diabetes.blogspot.com
publicjoshualevy at gmail dot com
All the views expressed here are those of Joshua Levy, and nothing here is official JDRF, JDCA, or Tidepool news, views, policies or opinions. My daughter has type-1 diabetes and participates in clinical trials, which might be discussed here. My blog contains a more complete non-conflict of interest statement. Thanks to everyone who helps with the blog.
