Testing for Blood Glucose Levels and Hemoglobin A1C

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Key opinion leaders in diabetes comment on various blood glucose tests to assess hypoglycemia and prevent future episodes.

Peter Salgo, MD: Now, I know Elaine went through some of the work-up for this. Once an episode has occurred—whether it is mild, moderate, severe, or whatever you want to call it—how do you start to assess this and prevent the next episode? We assume you want to prevent the next episode. Davida, could you walk us through this a bit?

Davida Kruger, MSN, APN-BC, BC-ADM: You certainly do it with education surrounding why you cannot miss a meal if you are on insulin, and why if you are going to be more active, you need to either lower your medication prior to that activity or be sure you take some extra food, protein, carbohydrates, when you are being active. We also really want anybody who is at risk of hypoglycemia—from my perspective, all people with diabetes—to be using something like a continuous glucose monitor [CGM], even more so than what we had been used to, which was self-monitoring of blood glucose, or finger sticks. Finger sticks do not give us what we need because what happens with finger sticks is that very often, patients say, “Oh, I am feeling low, I am just going to treat,” and we never know that they have had hypoglycemia, or we cannot get what is happening overnight. If a patient owns their own continuous glucose monitor, or there is something called professional CGM, where periodically we can place it, even though we would like every patient to own it—then we can see what is happening 24 hours a day, 7 days a week.

The other thing is that CGM cannot prevent low blood sugar itself, but what it can do is give alerts and alarms. Many of the CGMs can say, “Guess what? In the next 30, 60, or 90 minutes, your blood sugar is going to be less than 70 [mg/dL].” Then it will have a distinctive alarm for 54 [mg/dL]—the numbers or places where we are concerned. As health care providers, and also as we teach our patients, we can look at that data and we can say, “Look, we want, what we call now time-in-range in addition to A1C [glycated hemoglobin], we want your blood sugars to be about 70% time-in-range to have a really good A1C, but we also do not want you to have more than 4% blood glucose less than 70 [mg/dL], and 1% less than 54 [mg/dL].” That gives us all alerts and gives us data to think about.

We want to do education: what causes low blood sugar, the best ways to prevent it, but also how to treat it—how to treat it appropriately. We talk about 15 g of carbohydrates. We check your blood sugar in 15 minutes, if the blood sugar is still low, take another 15 g, follow it up with some protein. If you are going to be more physically active, either lower your medications, or you are going to have to take an exercise snack. If the patient is on an insulin pump, they have leveling for activity where you can set up the pump and say, “I’m going to do activity,” and it will lower your insulin. Then, we want every patient we possibly can to get continuous glucose monitoring; we would really like them to have it with alarms and alerts to help them be aware.

Peter Salgo, MD: You know what I did not hear? I have not heard of the oral glucose tolerance testing, the fasting blood glucose, or God help us, the 72-hour fasting plasma glucose test; are those all dinosaurs? Are they all gone?

Davida Kruger, MSN, APN-BC, BC-ADM: Well, we use some oral glucose tolerance testing for gestational diagnosis of gestational diabetes, but we certainly do not diagnose type 1 or type 2 diabetes utilizing those tests anymore. Folks, anybody else?

Anne Peters, MD: They are poorly reproducible and they are a burden on the patient, so usually we would do it based on glucose level and A1C. There are people, however, whose A1Cs are not all that helpful because of something abnormal with their red blood cells, particularly for African Americans; they may be better diagnosed with an oral glucose tolerance test. That being said, I just put CGM, continuous glucose monitors, on almost everybody and see what is really happening. I want to know the day in, day out glycemia, and I also know that glycemic variability has a lot to do with worse outcomes. I think that, hopefully, we are not going to need to do something as archaic as glucose tolerance tests in most cases, but with the pregnancy and diagnosing GDM [gestational diabetes mellitus], I think it is important to still do these tests.

Davida Kruger, MSN, APN-BC, BC-ADM: Yes, we still use it, but we have come so far. I have been in the field of diabetes treatment for 39 years and we have come so far in what we have to offer, not only in medications but also in the use of things like continuous glucose monitoring. 

Elaine Apperson, MD: You can have a great looking A1C: averaging 30s and 400s. I had a patient who was so upset today because their A1C had gone up a little, but guess what, we had worked really hard on eliminating a lot of hypoglycemia. She was that straight A student who wanted all of her numbers perfect, and she was so upset because her A1C had gone up. We tried to explain that it was so much better for her to be not having quite as much hypoglycemia, and we looked at her Dexcom [CGM system], and her time-in-range looked better; her time under 70 and under 54 [mg/dL] was better, but she still would not accept that things were better because her A1C was higher. With every [patient with] new onset I get, I usually get about 3 or 4 a week these days, we try to minimize the importance of A1C. We really try to minimize that because it is such a black and white thing that parents get hold of, and they get the idea that lower is better, and we do that to them.

Peter Salgo, MD: Did that girl get 1600 on her SAT [Scholastic Assessment Test] as well?

Elaine Apperson, MD: If she has not yet, she will, because she is that type of person. She was in tears.

Peter Salgo, MD: I want to thank all of you at home for watching this HCPLive® Peer Exchange. If you enjoyed the content, I want you to subscribe to our e-newsletter to receive upcoming Peer Exchanges and other great content right in your inbox.

Transcript Edited for Clarity