Cardio Care Now, Ep. 6

Clinical Pearls in the Use of Continuous Glucose Monitoring

Seth Martin, MD, MHS

In this podcast series, moderator Seth S. Martin, MD, MHS, examines key practice-changing clinical trials and explores the future of cardiovascular medicine, including the development of cutting-edge technologies, innovative approaches to implementing prevention guidelines, and more.

In this episode, Seth Martin, MD, MHS interviews Grazia Aleppo, MD, about key evidence for the benefit of continuous glucose monitoring (CGM) in patients with type 2 diabetes, the impact of CGM in clinical practice, and clinical pearls for clinicians managing patients with type 2 diabetes.

Additional Resources:

  • Battelino T, Danne T, Bergenstal RM, et al. Clinical targets for continuous glucose monitoring data interpretation: recommendations from the international consensus on time in range. Diabetes Care. 2019;42(8):1593-1603. doi:10.2337/dci19-0028
  • Szmuilowicz ED, Aleppo G. Stepwise approach to continuous glucose monitoring interpretation for internists and family physicians. Postgrad Med. 2022;134(8):743-751. doi:10.1080/00325481
  • American Diabetes Association Professional Practice Committee. 7. Diabetes technology: standards of care in diabetes-2024. Diabetes Care. 2024;47(Suppl 1):S126-S144. doi:10.2337/dc24-S007



Host: Hello everyone, and welcome to another installment of CardioCare Now with your host, Dr Seth Martin. Dr Martin is a preventive cardiologist and a professor of medicine in the Division of Cardiology at Johns Hopkins University School of Medicine in Baltimore, Maryland. The views of the speakers are their own and do not reflect the views of their respective institutions or Consultant360.

Dr Seth Martin: Welcome back to the CardioCare Now podcast. We’re really excited to have our next guest with us for an exciting conversation. This is Dr. Grazia Aleppo, who is a professor of medicine in the Division of Endocrinology at Northwestern Feinberg School of Medicine, where she also wears the hat of being The Director of the Diabetes Education Program. We had the pleasure of connecting at a cardiometabolic health conference in Boston, which had a focus on digital health, where Dr Aleppo shared some really fascinating science, insights, and clinical pearls related to the use of CGM in patients with diabetes. And I thought it would be really great for our audience to learn further from Dr Aleppo on this topic. Of course, Type 2 diabetes is a major risk factor for cardiovascular disease. It's been increasing in prevalence. It's a big problem, but we now have newer tools to manage Type 2 diabetes and related risks. So, we’re really thrilled to have Dr Aleppo with us to dive into this topic. Welcome to the podcast, Dr Aleppo.  

Dr Grazia Aleppo: Thank you so much, Dr Martin. It's a pleasure to be here with you today.

Dr Martin: Thank you so much. As we think about CGM and patients with type two diabetes, I wonder if we could start sort of zooming out with the broader problem. What is the big problem being solved by CGM in patients with type two diabetes?

Dr Aleppo: Type 2 diabetes patients develop diabetes when they're older and they really are not very used to checking their glucose. And so, we've been changing therapies based on the A1C every 3 to 6 months, if they're lucky, without really having any understanding of these patient’s fluctuations, and most importantly, the patient doesn't know where the glucose levels are. So CGM, with these 288 points per day of glucose, trend arrows, graphs, and information gives us and also the patient a plethora of information that really has this huge “Aha!” moment and say, “Oh, that's what's happening to me.” That is the number one thing that I find so useful for type two patients with CGM

Dr Martin: That’s really interesting. And, you know, you wear the hat of being Director of Education, and I imagine these “Aha!” moments are a great opportunity for education in a way that really connects back with the patient where they can see the relevance of understanding diabetes in general but also their specific diabetes as it's specifically affecting them and their health.

Dr Aleppo: And in fact, that is something when patients come to us and we do either a professional CGM or we put on CGM, the patient comes back with this sort of an “I understand what I can do for myself.” They're ready to accept changes in medication. For example, they always resist going on basal insulin or even a GLP because of injectables, and then when we show them what the glucose fluctuations are, they really have such a deep understanding and sort of relief because they say, “Okay, now I understand my glucose. I understand why you're pushing me to take a new medication” that they might have been very hesitant about. So, that is really so important because think about it, people with Type 1 diabetes, have been used to checking their glucose four times a day for years before CGM and that wasn't sufficient anyway. But Type 2 patients either resist or don't do it or want to forget. They have no idea what is going on behind their glucose every single day. So, that education program makes a huge difference and engages the patient in a way they've never been engaged before.

Dr Martin: Yeah, that engagement is so key. So, the CGM technology itself, I wonder if you could elaborate a bit more. I think our audience will have kind of variable levels of familiarity with CGM whether they've personally used it or how much they've been using it with their patients in practice. Could you just elaborate a bit more on the technology itself, what options do we have out there and how have these options evolved over time for CGM?

Dr Aleppo: Of course, well there are two main categories, that is professional CGM and personal CGM. In the professional CGM, the system is usually owned by the practices. We have the patient come in and we put the sensor on. They wear it for either 10 to 14 days, whether it's blinded, they don't see the data, or unblinded where they can actually see the data. They come back and they keep a glucose, food, and activity log, and we review it with them and that's the first time we actually see their data. Then the personal CGM has two categories, that is intermittent scanning and real-time data. So, the difference is basically the intermittent scan, you scan or tap the sensor transmitter that the patient wears on their arm to get the information transferred from the sensor to the reader. But the sensor usually has two or three components, that is a little film filament, which is the sensor. It goes inside the skin to check the glucose in the interstitial fluids, either because it's inserted every 10 to 14 days or every 6 months.

There are also implantable sensors, which is a whole different category, but still a personal CGM. And then basically they have either a transmitter that is part of the sensor transmitter unit or a separate exchange every 90 days. And then the information is sent to either a reader or a smartphone app. It can actually be shared with family members or even with the cloud where the providers can actually see the data. So, the effect of the sensor goes to the person first because they see the data every other minute. You also have a trend arrow and predictive alerts. So, the trend arrow describes how fast or how slowly the glucose is moving up or down, and it could give good information to patients. Let's say they're getting into the car and driving home, and they say, “Oh my glucose is going down. Perhaps I should eat a snack before I go into the car to avoid hypoglycemia.”

Similarly, they might have forgotten to take the medication for their meal. The glucose is going up. It says, “Wow, you’re going really high. Do something about it.”

As far as the alerts, the alerts are different kinds based on the brand of the sensor, but in general, the alerts are meant to just do that, tell the patient something is up, either the patient is going down or is already at a low glucose, less than 70 or even worse, less than 55, or the glucose is going up. So, how do we use these sensors and these alarms for people with Type 2? We want to try to avoid and limit, at all costs, alarm fatigue. So, we try to emit initially only the high alerts to make people used to actually seeing the data and not get overwhelmed. But we always put internal, the low alert, because that is very, very important and people with insulin are always at a risk for hypoglycemia. And so, they just change it every 10 to 14 days and they come to us sometimes asking for it. But in general, it's just this how the sensors are 10 to 14 days and then 180 days for the implantable ones. And again, personal vs professional CGM.

Dr Martin: Thank you so much. That overview is really helpful. And I wonder if we could now turn towards the benefits of CGM? What do you view as the key clinical evidence for the benefit of CGM in patients with Type 2 diabetes? What improvements in outcomes have been realized? And we would appreciate it if you could walk us through some of the key evidence.

8:05 Dr Aleppo: There've been a lot of studies with Type 2 diabetes just from multiple injections because in the past we thought that they were only for CGM or only for pumps, but that’s not true. All the way to people on one basal insulin or no insulin at all. And so the gold standard so far is still the hemoglobin A1C. And so, all these clinical trials, all of, have shown that CGM reduces A1C between 0.6 and 1% in Type 2 patients who are using this in clinical trials in the real world. And they also improve what we call the time in ranges. Since CGM has been brought to the market, there has been some consensus to standardize what these numbers are, what they represent, and what should we look for in terms of what we see as a good number or a bad number, so to speak.

So, the time-in-range includes the time-in-range, which is 70 to 180 mg/dL, which is supposed to be the standard where people should be most of the time, ideally 70% or more. So, any increase of time-in-range of 5 to 10% is clinically significant and shown to reduce some complications already. So, when you see that in the patients in Type 2 studies, you see that there is an increase in time-in-range in the target of 10 to 15 to 20% and a decrease in the very high glucose above 250 or above 180, for example. That's very, very meaningful. Some other studies showed a decrease in hypoglycemia, which sometimes we don't think too much about that. But people with Type 2 diabetes, especially those on insulin, have a great fear of hypoglycemia, and there is a lot of unrecognized hypoglycemia.

So, these studies show us that they have not only hypoglycemia, but we were able to decrease the frequency of it. And then in terms of the bigger picture, we have seen that there is a decrease of hospitalization, a decrease of acute visits to the emergency room. And these are done in thousands of people. So, it's either claim-based research or institution-based research that shows how the use of CGM in Type 2, that's not Type 1, Type 2 patients can decrease hospitalization, DKI, hypoglycemia, hyperglycemia, so many different things that can really be very costly. In fact, this is felt to be cost-effective. Now the one thing that I want to add is, that more and more research is being done on this topic is the patients without taking insulin on CGM. For example, a year ago, just about a year ago, a study was published, a randomized controlled trial, that showed that people who go for diabetes education plus CGM do better than diabetes education alone. I can see why that is the case because yes, diabetes education is paramount for patients, but when the patient is empowered to see in their own numbers, there is such an impetus to say, “Oh my gosh, I need to modify my behavior.” This particular study shows that people spend two extra hours per day in the target range and two fewer hours per day in high glucose. So, a lot of data coming out that supports how CGM can be beneficial in Type 2, whether you take insulin or even without taking insulin.

Dr Martin: Really interesting. Thank you for diving in there. And I guess then to move beyond the clinical trial evidence to your practice, I'm curious how CGM has changed your clinical practice over time. You've already shared about the power in terms of patient education engagement. I imagine you're seeing patients have more time in range and so forth. Maybe you could share just a little bit more about what it's like on the front lines using CGM commonly in your practice and also just for clinicians, how you find it logistically in terms of ordering it, getting insurance approvals, and so forth. How much effort does that require? How smooth is that for you in your own clinical practice?

Dr Aleppo: So, the good news is that since April of last year, Medicare has actually expanded the CGM coverage to include people with just one injection per day or actually any insulin per day and risk for hypoglycemia. So, that has made a huge change in the coverage. And so as of now, which is January 2024, other insurance companies are covering CGM for people on just one injection per day of insulin and or hypoglycemia. So, if you ask me that question three years ago, it would be much more difficult for Type 2. But now it's very easy, so much so that if a patient comes to us on basal insulin, the first thing we do is to put them on continuous glucose monitoring for two reasons: (1) they're not checking their glucose. (2) I have no data and; (3) they have no idea where the glucose levels are. So it's really three points.

Now in clinical practice, I can tell you people have told me so many stories of how it has changed their lives. It makes my life so much easier because imagine me 10 years ago with this, sort of, a glucose log with some blood on it, fake glucose numbers taken twice a week, and I had no idea what I was doing recently. But now with this enormous amount of data that is going on the cloud directly, I can just get the data in less than two seconds, literally. So, what I do at the clinic is the patients have their smartphones, most of them. And so, the data is already connected to our cloud at the clinic because when we start the patients on CGM, we connect them immediately. So, there is no uploading. You can just look at the computer, click a couple of tabs and see their numbers, turn the computer screen, and we dive into the data and say, “Okay, what is bothering you today? What do you want to tell me about the last few weeks?” And they say, “I want to show you this, this and this, what happened to me, what didn't happen.” So, the patient comes with questions. Instead of me directing the visit, it’s the patient who directs the visit. It’s great.

As far as the insurance: so again, when people are on one injection per day, we start CGM. The multiple daily injection is a given. It's standard of care. Everybody covers this. So, it should be done for everybody. Challenges about coverage are as far as whether it's pharmacy benefits vs DME, which is durable medical equipment, that is based on the patient's insurance, and the fact that for Medicare a patient needs to be seen every six months so we can send the chart notes and they can continue to receive their CGM. You know, six months of frequency is a pretty good frequency for visits for diabetes anyway, so it doesn't affect us so much.

But I really feel that the human component is what we have forgotten about. The patient feels so much better about their condition, it's a very difficult condition to have diabetes. It's so stigmatized, so many things are bad about it. Instead, they now see their numbers and say, “Yes, I know I was doing something not so good that day. But look, on this day I actually was able to get to my target.” So, when somebody is engaged and empowered, there is no better thing for us. It's easy for us to look at the data. The patient can contact us remotely and say, “I've had a really bad problem. Can you please take a look?” Of course, you go into the software, or better yet, we have actually integrated CGM in our institution into the medical records. So, I click on a couple of tabs and look at the data, send back a message, and in between touchpoints or in between visits, the patient can make a meaningful change instead of waiting six months to make an adjustment. That can put the patient in much better control before the six months or the three months. So, there are many, many facets, but it's changed, and it's incredibly improved the quality of care we provide for a patient.

Dr Martin: Yeah, thank you for that description. It seems like it's been a really transformative technology for your clinic and for many clinics. Thank you so much for sharing that. I'm curious, as clinicians are looking to adopt more CGM in their practice and thinking about which patients are the best fit for this if you could share a little more about patient selection. What key considerations or tips do you have for other clinicians when finding the right patients for CGM?

Dr Aleppo: In a way, every patient is the right patient because there is so much involvement. The patient doesn't have to do much. Think about the difference between having to prick their fingers, all this blood, it's painful, it's dirty. This is something that goes passively into their phones and they can take a look at it. So, as far as patient engagement, honestly, every patient on insulin should be on this, and very often patients come and say, “Hey, can I use this thing on my arm?” And I say, “Let's look at it and see if you are eligible for therapy.” Sometimes when patients are on oral medication, they might not be able to use it because their insurance might not cover it. But if they're hypoglycemia, absolutely yes. So I would say patients with hypoglycemia or multiple daily injections have to be offered CGM, and I found so far nobody says “no,” unless it's a cost issue, of course. So be very attentive to that and understand that.

So, you might not be able to afford it based on the insurance. As far as the other things that are important to mention, it’s not just patient selection, but rather patient education. Even though these systems are very easy to use, you need to train the patient on what the numbers mean, what the arrows mean, and what the troubleshooting is between, for example, the lag time. This is not blood glucose, it's interstitial fluid glucose. So, there's always going to be a delay. If they try to contrast and compare, they might get frustrated because they're never going to be the same number, but they're not supposed to be the same number. They're in two different places at two different times. This becomes particularly relevant when you do hypoglycemia treatment because the glucose in the center lags behind a bit longer, whereas the glucose in the bloodstream normalizes faster.

So, there are little tricks to address the alarms and avoid alarm fatigue. Understand how to properly start the sensor, and what the alarms mean. This is not a 2-hour training. It's maybe 30 minutes, but it's a very important 30 minutes. And in our practice, the nurses do it, not the educators. They're too busy with doing the classes. So, it's not this huge effort in terms of staffing. It doesn't really take much, but it's very important to give the first training so they get engaged, and once they get engaged, use it correctly. If you just give them a sensor and don’t look at the data, they feel ignored and there is no difference between that and the glucose log, which we never looked at. So, make sure the patient looks at the data and we look at the data and engage with some feedback for them.

Dr Martin: Yeah, this is really helpful. So, as you speak, you're starting to get in some clinical pearls related to the lag between blood and interstitial glucose levels. And I hear how important it is for that education piece and to prioritize it upfront so patients can really find a system that's serving them and not frustrating or confusing. I wonder if you have any other clinical pearls that I haven't necessarily asked about that you would want to share?

Dr Aleppo: So, when we put the patients on CGM, we tell them, “Please don't be afraid of the numbers you're going to see.” Because they're going to see these high numbers. I say “You've had these numbers for many months. Just know that it's going to get better.” Because I don't want them to get discouraged because the amount of information might be a little bit overwhelming because there's a lot of information. In fact, when for example, we do professional CGM, the first few weeks of personal CGM, we tell them not to overdo it. Just look at the data, try to work with what it tells you, and monitor, let's say post-meal fluctuation. See if you can modify the meal. And sometimes we give them actually homework and say, for these first few days, do this in terms of don't take, for example, more insulin or one extra pill of medication just because you see a high glucose.

Rather figure out what caused that high glucose. Was it a specific meal? Was it the timing of the medication administration? And so that makes the patients less overwhelmed because I tell you when the A1C is 9 or 10% and they'll see 350, they get really scared and they think all of a sudden, “Geez, I'm going to have something major.” Where they've had this for months, they just don't know about it. So having that up-front information, say, “You are going to see some high glucose, don't worry, this is part of why you're here. We're doing this together so you're going to get better with time. Just know that this is going to be a time when you're going to look at the glucose and say, ‘What can I do to make it better?’” Once you get that information, first, it's not threatening, it's not scary, it encourages the person and makes them feel safer. That, I think, is very important to make the person feel confident that they can do well with this new tool.

Dr Martin: Understood, understood. Well, this has been a fabulous conversation, and very informative. I wonder for those listening who are interested in diving into CGM even more, what resources you might point folks to for further reading or any ways to learn more about this topic?

Dr Aleppo: Yes, of course. So, the one thing that I would suggest is to go to the American Diabetes Association Standards of Care, Section 7. It talks about diabetes technology. Also Battelino and colleagues' paper, which is the consensus on CGM metrics, which was published in 2019 on Diabetes Care, really gives you an explanation as to what the CGM metrics are, why they were there, and how to look at the values, glucometrics. Finally, my colleague and I, Dr Szmuilowicz and I published a paper for primary care, internist, and family practice on how to interpret CGM, which was published on Postgraduate Medicine in 2022, to help the provider in really five minutes to understand what is the problem, where is the problem, and how to adjust therapy in three simple steps so it doesn't become overwhelming for the provider who has 10 minutes for the visits and is able to help the patient and do meaningful changes in the therapy with the information provided by CGM.

Dr Martin: Those are really helpful resources. So much appreciated. I want to just thank you for taking the time to share your expertise with us today on CGMI. I know it's going to be very valuable for our audience and I hope to get to see you again sometime soon at one of the upcoming conferences.

Dr Aleppo: Yes, thank you so very much for having me. It's been a true pleasure. Thank you so much.

Dr Martin: Thank you, Dr Aleppo.

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