Defining Hypoglycemia Through Blood Glucose Level

A multidisciplinary panel of experts shares insights into identifying symptoms of hypoglycemia and highlights the importance of stratifying level 1, 2, and 3 blood glucose levels when making the differential diagnosis in diabetes.

Peter Salgo, MD: You know what I’m hearing—I hear the list of symptoms of hypoglycemia, but I also hear that there were other conditions and other syndromes that can produce some of the same symptoms. How do you parse this out? Is it that you say, “This patient is diabetic and has these symptoms, therefore he’s hypoglycemic?” Or do you really have to be more careful of that? Elaine?

Elaine Apperson, MD: Sometimes, for kids who have diabetes, it’s all too easy if mom says, “When he woke up, he was kind of sweaty. He seems sort of out of it. I gave him something to eat because that’s what I usually do. He seemed to get a bit better.” It’s very easy to say, “He probably had a low,” but you must do a deeper dive than that. It’s important to make sure that at some point that episode has a documented blood sugar to go with it that’s in the low range.

What you know about hypoglycemia is that it should respond to active, fast-acting carbohydrates and that the patient should improve within minutes, meaning that their physical signs of distress—like an elevated heart rate and sweatiness—should go away. Their cognitive processes should be restored to normal after they receive those carbohydrates, and it should happen quickly. If not, then they possibly have had a seizure unrelated to diabetes or something like that. If it’s a case of an adrenal issue a or cardiovascular issue, then there should be a differential diagnosis and you, as a physician or as a nurse practitioner, need to go down the list and make sure that you don’t just assume.

Peter Salgo, MD: You don’t want to miss something, right?

Elaine Apperson, MD: No, you don’t.

Peter Salgo, MD: Somebody who has syncope—you don’t want to miss a seizure, you don’t want to miss a primary arrhythmia, and you don’t want to miss a TIA [transient ischemic attack].

Elaine Apperson, MD: No.

Peter Salgo, MD: When is it appropriate to pull the rip cord on this and do the full-blown, turbo-charged work-up for the symptoms we’ve been discussing?

Elaine Apperson, MD: If you have repeated episodes in which somebody appears to have hypoglycemic episodes but is not responding to fast-acting carbohydrates—we often get patients with hypoglycemia referred to us who do not have a diagnosis of diabetes. In all those instances, if we don’t have documented low blood sugars, we get them on continuous glucose monitors [CGMs]. If they do have documented low blood sugar and they don’t have a diagnosis of diabetes, we have a set of critical lab tests that we always do looking for metabolic abnormalities, adrenal issues, and cardiovascular issues. We go down the list.

Peter Salgo, MD: For the record—I know we’ve been over this before, but I really want to nail it—give me a definition of hypoglycemia. It can be according to anybody’s guideline; I really don’t care. Is there a set number? Is it 70 mg/dL? Is it 60 mg/dL? Or is it 40 mg/dL? What is hypoglycemia?

Anne Peters, MD: A few years ago, the FDA came to a number of societies and said, “We need a definition.” The reason they needed a definition is not because people were confused but more because the research studies that were done from 1 company differed from another company in terms of the definition of hypoglycemia. When you are studying a product from company A to look at rates of hypoglycemia, you want it to be defined in the same way that company B defines it. We used to call hypoglycemia mild, moderate, and severe. Mild is the kind we are talking about with adrenergic signs and symptoms. It’s not that low; it’s maybe 65 mg/dL. Moderate was lower than that, and then there were the severe cases, where people passed out from hypoglycemia.

We had patients on the panel who said, “We don’t want it called mild to moderate and severe.” To a patient, it may be that hypoglycemia of any sort feels severe because they hate it. You’ve been hearing how this can really limit patients’ lives, so they didn’t want a subjective term. There are some really smart researchers—Elizabeth Seaquist is 1 of them—who look at levels of hypoglycemia and what happens to your brain. There was a huge argument about whether to use 54 or 56 mg/dL, or who knows what—there were hours of arguments. Below about 54 mg/dL is where you start losing measurable cognitive function. You can’t do certain word-finding tasks and math problem solving, or do whatever they were studying. These may be subtle, but that was pretty much the point at which people started losing those symptoms. 

What they decided was that between 54 and 70 mg/dL, we’re going to call it level 1 hypoglycemia. Some hypoglycemia experts didn’t want to call that hypoglycemia because they thought hypoglycemia started at 54 mg/dL. But clinically, I want to know if somebody is below 70 mg/dL because I don’t want them to be below 54 mg/dL or they’ll feel symptoms. With a lot of consensus—and gobbledygook—we finally got to level 1, which is at 54 to 70 mg/dL; level 2, which is less than 54 mg/dL; and level 3, the severe type of hypoglycemia, where you can’t treat yourself and someone else has to treat you. We have those levels: 1, 2, and 3. It makes it easier now that we have a definition. Those are the official definitions for hypoglycemia. It’s measured, and it fits in those levels.

Peter Salgo, MD: I want to thank all of you 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 in-box.

Transcript Edited for Clarity

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