Anne L. Peters, MD, CDE: Hi. I am Dr. Anne Peters, Director of the Clinical Diabetes Programs at the University of Southern California. Today I am joined by Dr. Howard Wolpert, Senior Physician, Section of Adult Diabetes, Director of Continuous Glucose Monitoring (CGM), an insulin pump program, Joslin Diabetes Center, Boston, Massachusetts. Welcome, Howard.
Howard A. Wolpert, MD: Hi.
Dr. Peters: Last year we talked about the current state of CGM in diabetes. I would like you to talk today about what sort of advances we have made in the past year.
Dr. Wolpert: At the American Diabetes Association (ADA) sessions, which we are currently attending, a number of exciting new developments have been reported. Some of them relate to the use of closed loop control devices in the clinical research center. These are devices with a CGM linked to an insulin pump and a control algorithm so that the insulin delivery by the pump is regulated on the basis of the output from the CGMs. In essence, it's like a mechanical pancreas.
The studies that have been reported in patients with diabetes are very promising. They show that both hypoglycemia and hyperglycemia can be minimized. Obviously, these are short-term studies that are conducted under careful clinical observation in inpatients. The next step is going to be taking these into the outpatient arena.
The other interesting development, which I think will have a more direct impact on patient care, is an earlier version of a completely closed loop system where the delivery of the pump basal insulin (the continuous insulin) is regulated. It's shut off if the glucose level goes low, so these are so-called low glucose suspend pumps. They have a major potential utility in terms of minimizing hypoglycemia at night.
Two papers have been presented.[1,2] Both of these studies were done in Europe where they have shown benefit in that respect. Part of the challenge that we are facing here is, as you know, these devices don't yet have US Food and Drug Administration (FDA) approval so they are not available, but one of the encouraging developments just over the past week is that the FDA came out with new guidelines for industry and for the types of clinical trials and endpoints they want for studies to get approval for these devices. That is going to be an important advance that will have an effect on patients in the very near future.
Dr. Peters: Let's talk a little bit about these devices because it's interesting and important to understand. We have patients who are on continuous glucose sensors, and they presumably alarm to tell the patient that their blood sugar is low, but as we know because we have many patients who have these devices, people will ignore the alarms or sleep through the alarms or they just won't respond to the alarm. This is why these devices or systems that actually will turn off the insulin delivery seem to really help. I have been really impressed with that kind of data.
Dr. Wolpert: Yes. It's really an important development. Although CGMs clearly have been a benefit in terms of minimizing hypoglycemia, particularly at night people will sleep through the alarms and that's when people are most vulnerable from hypoglycemia.
One of the important steps that needs to be established in the clinical trials is to ensure that having inappropriate suspension of the insulin delivery, which is obviously an issue given the fact that the sensor accuracy is still not 100%, particularly in the hypoglycemic range, doesn't lead to deterioration in mean glucose and A1c. The studies from Europe have been pretty encouraging in that respect. Neither of the studies has shown that problem, but they were short-term studies and they weren't powered adequately to address that important issue.
Dr. Peters: What do you think about what's happening with the development of sensors? Are we getting better, more accurate sensors? Are they getting easier to prescribe for patients?
Dr. Wolpert: On that front, there have also been important developments. Two of the companies here at the ADA, both Dexcom and Medtronic, have actually reported on their newer CGM devices. Both of them promise improved accuracy, particularly in the hypoglycemic range, which as we discussed is really the real problem for many people with diabetes.
The other advance is that the companies are realizing that the devices need to be more user-friendly, and some features in both of the devices are improvements in that respect. With all of these developments, the technology is going to be easier to use and more people are going to start adopting them in their diabetes care.
Dr. Peters: Now what about the issue that we see a lot -- people will wear these devices for a little bit but then stop wearing them. What's your advice about using these more continuously? I certainly see in my patients that there is an enthusiasm and then a waning of the enthusiasm for wearing them.
Dr. Wolpert: Some of the challenges here reflect the limitations of the technology. As we were discussing earlier, the alarms are a lot of the benefit, but because of the fact that the devices aren’t 100% accurate, people often get false alarms. Both of us have heard many stories from patients who find that their sleep ends up being disrupted because of the alarm. As the accuracy improves, that will lead to improved adherence in terms of using the technology.
Dr. Peters: I think that will help. There are definitely a lot of complaints, both from the patients and their husbands or wives who sleep next to them, that everybody is being awakened all the time.
My last question is that everybody always wants a way to test blood sugar levels without pricking the skin -- some sort of magical, ethereal way of knowing what blood glucose levels are that is simple and doesn't require blood. Do you think that is ever going to happen, or do you think that the technology as it stands will still require finger sticking and placing devices subcutaneously?
Dr. Wolpert: We may see some improvements in that respect. As CGM technology improves, we are going to have CGM devices that will be factory-calibrated, just like the finger stick needles. I can certainly envision -- and I know technology is in development -- where one would have a CGM device that would be implanted and would be self-calibrated. A person wouldn't have to do any adjunctive finger stick measurements in order to use the technology. That is probably feasible on the basis of work that I have already seen.
The issue there, though, is that people are still going to have an implanted device. A catheter sensor is going to be passing through their skin, so it's not as though they are going to be totally free of sticks.
Dr. Peters: No, none of this is magical or easy yet. I really feel that at this meeting more than any I've been to recently, I have seen at least hints of real progress in terms of developing these systems.
Dr. Wolpert: Exactly. What I got a sense of is a real excitement that finally there is progress. As I mentioned earlier, there are a number of groups reporting on closed loop technology, and the CGM devices are improving, so there does seem to be a real momentum in terms of technology improvement for people with diabetes.
Dr. Peters: Thank you, Howard. This has been Dr. Anne Peters reporting from the ADA meetings in San Diego speaking for Medscape. Thank you.
Medscape Diabetes © 2011
Cite this: Anne L. Peters, Howard A. Wolpert. Improving Continuous Glucose Monitoring Technology - Medscape - Jul 06, 2011.