DR. KUSHNER: It is now recognized that patients with similar hemoglobin A1c (HbA1c) levels can have different glucose variability patterns and rates of hypoglycemia. Patients can use continuous glucose monitoring (CGM) as a tool to spend more time in the target glucose range. With the goal in mind to familiarize clinicians with the utility of such devices, a panel was convened to discuss this technology.
We’ll start off by asking Gene, have you suggested CGM to a patient who is on oral anti-glycemic agents?
DR. WRIGHT: The use of CGM in patients who are on oral agents, I think, really depends on what type of oral agent they’re on. Sulfonylureas, particularly in older patients, are agents for which I think CGM can be very revealing. Yes, I have used it with oral agents. Sulfonylureas can induce hypoglycemia that is often not recognized by the patient and clinician.
DR. KUSHNER: How about you, Isaiah?
DR. PITTMAN: I do quite a few insulin pumps and quite a bit of CGM, both professional and personal.
With that being said, I look at CGM oftentimes as a modernized way of patients being able to check their glucose or a way that—we can see clearly from the FreeStyle Libre (Abbott Laboratories, Abbott Park, IL)—will eventually replace the basic finger stick self-monitor glucose check. I find it is useful pretty much across the board from the standpoint, as Gene has already mentioned, to evaluate hypoglycemia that may go undetected from agents that are hypoglycemia-inducing and in patients with impaired hypoglycemia awareness.
At the same time, a picture is a thousand words. It’s much easier to explain the idea of glucose control to patients by using an image from CGM versus having them look at their glucose, which a compliant patient may do four times a day.
Oftentimes, not just the patient but many clinicians will have difficulty with four-times-a-day glucoses after one month of readings. Then what do you do with those data, whereas they can see that continuous tracing from a CGM and it’s incredibly useful. This helps the patient to understand “I’m high here. I’m low there.” There’s a pattern to it. It’s continuous day after day.
DR. KUSHNER: Excellent. I agree with you both that continuous glucose monitoring is a very useful tool and a more modern way of evaluating glucose control. We have been very glucose-centric as a society, just looking at what is this glucose measurement right now as opposed to what the variability and pattern are in each individual patient.
I feel that Gene highlighted the most important type of oral medication, which is sulfonylureas for the purpose of avoiding hypoglycemia. We’ll talk more about hypoglycemia as we go along, but as was mentioned, this technology helps patients who may have a hypoglycemia unawareness with oral medications in addition to those who are insulin-dependent.
I would ideally use CGM in any patient who is not where we both decide that we want them to be. I think that it enhances shared decision-making and defines the goal of time in range in addition to HbA1c.
CGM helps to give people “teachable moments” and helps them become more motivated and involved in their own self-care by seeing what effect their diet has on them, specifically the role of carbohydrates and fats. It also gives patients a deeper understanding of the value and risks of exercise.
Considering that diabetes is not a disease that is solely managed based on medication but involves patient self-care, what better way to get them involved in their self-care than for them to recognize their trends and what they’re doing day by day. This technology helps to facilitate a conversation with the patient to say, “Maybe there are different changes in either your medication therapy or self-care that we could help you implement.”
DR. WRIGHT: Great. Well, Pam and Isaiah, I think what I’ve heard you say is that you also use this for behavior modification for the patient. Once they see their glucose or glycemic patterns throughout the day, they are now able to put some context to that individual number.
I have also found when I have patients check their self-monitoring of blood glucose (SMBG), they get a number. That number rarely has context for them unless it’s too high or too low.
Anything in between is kind of fuzzy, but I find that with an ambulatory glucose profile, the context that comes with that now gives them better definition about “Oh, it is high and it’s going higher” or “It’s low, and it’s trending lower.”
DR. PITTMAN: Exactly. I just finished clinic before we started this discussion and was explaining to a patient, as I oftentimes do, that the true management of diabetes is not treating hyperglycemia, it’s preventing hyperglycemia.
DR. WRIGHT: I agree.
DR. PITTMAN: The way to show patients that they are basically treating high blood sugar is to show them that the blood sugar is already elevated. When they can see what a non-diabetic sees, which is glucose that barely elevates with a meal, then they get a true idea.
When you look at a CGM, they get the idea that the blood sugar is going up as I eat a certain meal or the blood sugar is going down when I’m not eating. That’s clearly depicted when looking at a CGM, and it gives them an idea of “Am I in a physiologically normal pattern?”
Not necessarily a number—as both of you have stated— but does this pattern look normal? The blood sugar is basically staying within a consistent range, whatever that range; whether they understand that full range or not, is it staying relatively consistent?
DR. WRIGHT: That gets to another question. How does CGM better help us as clinicians manage diabetes? From my perspective, it helps to engage the patients more with their management.
DR. PITTMAN: Absolutely.
DR. WRIGHT: I have a very different conversation with the patient who’s on the CGM than I do with a patient who is not, because I’m doing more listening and letting them tell me what’s going on.
DR. KUSHNER: Right.
DR. WRIGHT: I coach them along with “What other choices might you make in these situations?” It is a very, very different conversation that we have as a result of the CGM report.
DR. KUSHNER: I think that’s an excellent point. I no longer have patients on oral medications give me a fasting glucose value every day. In my opinion, there is very little value that the patient or I am going to get from that measurement.
What I have started to do with my SMBG is to have patients give me 7 measurements 4 days a month. That way the patient has the advantage of seeing how their glucose is doing on those days that they did the 7 measurements. It is a burden but is more useful. However, with CGM there is less of a need to do that anymore. I’m getting much more from a CGM than 7 measurements in a day, and the patient diary helps bring even more value.
The conversation is different. The motivation is different. The patient’s understanding and involvement are different, but also what you said, Gene, is important: The physician or the health care provider’s involvement is different. I think this is an advantage that is often not recognized.
DR. WRIGHT: Well, I think in terms of time management, it actually helps you speed your office visit along on the diabetes portion of it.
DR. PITTMAN: Absolutely, it does. That goes back to a statement that I made earlier when a picture really is a thousand words. When patients see their CGM, they understand exactly what you’re referring to in terms of the term glucose fluctuation or blood sugar fluctuation.
They understand what you mean because they can see it going up and down at a given time of day. It absolutely makes things faster for communicating with the patient and, looking at those data before you even walk in the room, being able to interpret what you’d like to do and what conversations you want to have.
DR. KUSHNER: Let’s move on to what HbA1c level the patient needs to be at before you would consider using a CGM. What are your thoughts?
DR. PITTMAN: We do a professional CGM. Again, there’s a difference between personal and professional and different rationales behind them. We would use a professional CGM with pretty much all of our patients.
The HbA1c doesn’t determine it. The reason is that if they’re diabetic, whether they’re a type 1 or type 2 diabetic, glucose variability is what we want to prevent. Going back to what was stated earlier, from the standpoint of normal physiology, there’s only a small degree of variability.
As a result, to try and normalize things with the CGM, whether the HbA1c is 6.6% and the patient doesn’t realize that they’re having a hypoglycemic episode or hyperglycemic episode until you use a CGM or the HbA1c is 9%. The reality of the matter is that patients can see where you’re trying to get to. They can see that variability with the CGM, when it’s used professionally.
Then when they have it on their own for a personal CGM, whether it’s an insulin pump patient, multi-dose injection patient, or a patient who’s on oral meds, they can see that glucose variability. That’s incredibly useful to them on a day-to-day basis. I don’t think HbA1c
plays a huge role.
DR. WRIGHT: I couldn’t agree more with you. I agree that the HbA1c doesn’t determine who gets the CGM. There are patients, certainly with low HbA1c levels, where you suspect hypoglycemia, but it is more concerning in patients who have high HbA1c levels where you don’t suspect hypoglycemia. I’m aware that there are studies that show that even at an HbA1c of 8%, 8.5%, and 9%, patients can have frequent and severe hypoglycemia at an HbA1c level where most people would say, “Oh, just push ahead with more therapy.”1
I think when you peel the onion back on the HbA1c, it really is just an average. That average is influenced by a lot of things, and the variability—you’re absolutely right, Isaiah—is from the bottom to the top. All of those numbers in between are where you really can see on the CGM what the HbA1c doesn’t give you.
DR. KUSHNER: Where would you find the measurement and describe what the measurement is for variability? If you have a CGM in front of you, what are you looking at and in what order?
DR. WRIGHT: Well, I look for the risk of hypoglycemia first. Are there times of day when the blood sugars are running low? Then I look at the variability at different times of day, typically around the meal, so that if there are some meals associated with blood sugars of 100 and some associated with blood sugars of 300 at the same meal, that might suggest a behavioral component. We as humans tend to eat different things on different days at the same meal. That may contribute to the variability.
Then the third thing that I look at is where the high blood sugars are occurring. What are the kinds of things we can both do with medication and behavior? After addressing the low risk and the variability, what are the things we can do with medications and behavior to then bring that into more of a reasonable range?
DR. KUSHNER: What do you think about that, Isaiah? What are your thoughts?
DR. PITTMAN: I would agree. I first look for hypoglycemia, which is why on pretty much every CGM—I don’t care whether we’re talking about Medtronic CGM systems (Medtronic, Fridley, MN), Dexcom CGM (Dexcom, San Diego, CA), or FreeStyle Libre (Abbott Laboratories, Abbott Park, IL)—it’s below the red for a reason. They’re trying to grab our attention. Whether you’re looking at a pie chart or a bar graph, their mark is red when they’re low.
Whether they’re low or high, the discussion that I’m having with the patient is normality. We’re trying to get you to normal glucose levels. As Gene alluded to the HbA1c not being reliable, I was taught very early on a little story that I’ll share.
The HbA1c, I was taught, is like the average temperature. One of my attendings when I was a resident would say that if you’re not from the United States and you pick a place to live, then you would say, “Well, Oklahoma City is as reasonable a place to live as San Diego because in the almanac the average temperature is close to the same.” You have no idea that Oklahoma City is incredibly cold in the winter and incredibly hot in the summer.