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Prof Richard Bergenstal: First step towards an artificial pancreas

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First step towards an artificial pancreas





Hello! You’re on MD-FM INSIGHT, the first medical web radio. Today we’ll be devoting our "Question & Answer" program to blood sugar monitoring in type-1-diabetes.

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One of the main concerns with insulin pumps today is the risk of “overcorrecting” high blood sugars if users aren’t careful. Last June, at the annual meeting of the American Diabetes Association, in Chicago, Pr. Richard Bergenstal, director of the International Diabetes Center in Minneapolis, presented the results of the ASPIRE study, in which his team tested a new type of insulin pump, which automatically detects and responds to low blood sugars.


Dr. Bergenstal, first tell us what was the goal of the ASPIRE study:

Bergenstal-1: “The goal we are always going for in diabetes control is good blood sugars, good A1c but avoiding hypoglycemia. So this was one of the first large trials that said: could we put some intelligence into the pump? –the pump already has the blood sugars that are being sent to it from a continuous glucose sensor but now, could we tell the pump to act on those numbers and, if it sees that the blood sugar is low, shut off the delivery of insulin for up to 2 hours to allow that blood sugar to drift back up and prevent a serious hypoglycemia and still maintain good glucose control.”


Ok so: it’s a pump that suspends the delivery of insulin -when blood sugars get low. Can you use pumps available today to do that?

Bergenstal-2: “So we’ve had insulin pumps for 30 years, we’ve had sensors for 5 to 7 years that measure the blood sugar every 5 minutes, send the numbers to the pump but, for the first time now, we are evaluating software in the pump that can read those sugars and automatically adjust the insulin. So we’re putting intelligence, we’re putting brains in the pump. This has been studied in small studies around the world and this is the largest randomized trial to really test this feature.”


Ok and so when does this “intelligent” pump shut off?

Bergenstal-3: “We had to set a threshold level to shut off the insulin, and we picked 70 mg per deciliter because that’s the standard in the US and pretty close to the standard around the world whereas to where the definition of hypoglycemia begins.”


And so what exactly did you look at in your study?

Bergenstal-4: “So since you have continual blood sugars being measured, you can look at all the blood sugars over a period of time, so we took 10pm to 8 am, and we looked at all the blood sugars. What you do is you draw a little curve and you say: how many blood sugars were under that mark of 70 for the whole nighttime? --that’s a good measure of the duration of being low and the severity of being low. How much total exposure to low blood sugars do you have. So it’s the most scientific measure. We also measured just how many events that went down, we  measured how often they got to 50, 60 and 70, but the area under the curve is sort of the most precise measure.”


And what did you find?

Bergenstal-5: “So we were pleased that this study met its objectives –it showed the primary outcome: You can reduce the values under 70 by 40 percent, particularly overnight, we could reduce the values under 60 by 50 percent, and we could reduce the values under 50 by almost 60 percent, and we can do this without any elevation in the overall blood sugar.


Ok so: you also looked at values under 70…

Bergenstal-6: “Right, so the other finding that we found in this study is that we’re all hoping to get rid of severe hypoglycemia. Severe hypoglycemia is defined as an episode where somebody just couldn’t take care of themselves –somebody else had to help them. They were at risk for a seizure or coma or emergency room visit. We saw none of those in the group that used the threshold suspend whereas we saw four of those severe events in the other group. So we are optimistic that this is not only reducing general hypoglycemia but has the potential to reduce the most dreaded and feared severe hypoglycemia.”


But if you suspend insulin delivery, aren’t blood sugar levels going to shoot back up and provoke the opposite -- hyperglycemia?

Bergenstal-7: “Right but we saw that after two hours it only went up to 92 grams per deciliter –right into the middle of normal range. So we were pleased that we’re not worrying about dramatic rebound or high blood sugars when you suspend.”


Ok and so what’s the next step?

Bergenstal-8: “So we think this is the first step along the process of developing the artificial pancreas and we’re pretty optimistic that we’re going to see more and more studies to expand this. I think it’s going to go stepwise, I think the next advance will be: We’ll predict when it’s going to get low and shut it off. Then I think the next advance will stop it when it gets high and we’ll put a little extra insulin. And the we’ll go to maybe two hormones in a pump: glucagon when you are low, insulin when you are high, and those will come over the next five years or so. There are studies already at the American Diabetes Association meeting on each one of those new innovations. We call them feasibility trials –20 patients in the hospital, 15 patients in the clinic… but if those pan out like our study did, then we’ll have more and more advances coming over the next five years.”


So what’s your take home message for practitioners?

Bergenstal-9: “I think the take home message is: this is a time to be optimistic. What we’ve all been hoping for is having an artificial pancreas. I think this study says we have the first phase of that right now, and we can look forward to more advances. This is about helping our patients, so to prevent the dreaded and dangerous low blood sugars now and, eventually, keep that low blood sugar in a target range as much as we can.”



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See you soon on MD-FM.


Previous editions


Best of Science in Nutrition 2013: Yogurt for a healthier diet (EB & IUNS 2013)

Best of Science in Nutrition 2013: Yogurt for a healthier diet (EB & IUNS 2013)
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