This transcript has been edited for clarity.
We've all been hearing about the weight loss benefits of glucagon-like peptide 1 (GLP-1) receptor agonists, but it's important to remember that they are also diabetes medications. If you have a patient who's on an insulin secretagogue and/or insulin, it's important to remember that you need to adjust those medications to avoid hypoglycemia as you start and uptitrate the GLP-1 receptor agonist.
This isn't really cookbook, in the sense that you have to think about each patient, but I'll tell you what I do. First, I try to have most of my patients on continuous glucose monitors (CGM) because if they're on CGM, I can look at the trends to see what's happening as I'm adding a GLP-1 receptor agonist. If they're not on CGM, it's helpful if they test a fasting glucose level and perhaps a postprandial, though it's harder to get people to do, because you want to know whether to reduce the basal insulin or the prandial insulin.
Regardless of testing, you need to review with the patient the signs and symptoms of hypoglycemia and how to treat it if it occurs. In a patient on insulin, you may want to make sure they have glucagon at home because there have been episodes of severe hypoglycemia when a GLP-1 receptor agonist was added to insulin.
As a rule of thumb, I start by looking at the A1c. If the A1c is above 8%, I'm probably not going to do much reduction in the insulin secretagogue or the insulin right off the bat. I'll watch the patient as they begin to respond to the GLP-1 receptor agonist and then start tapering down the insulin if their glucose levels fall.
I often reduce the prandial insulin levels first because you're going to start seeing the patient eating less and be at increased risk for hypoglycemia between meals. If I start seeing the fasting glucose fall, then I'll start reducing the basal insulin. Usually, I reduce the doses by 10%-20%.
As I said, in somebody who starts out with a higher A1c, I don't right off the bat reduce the insulin. I watch what happens as the dose is increased. As the dose is increased in someone who's on an oral insulin secretagogue, I'll tend to cut that dose in half as I see glucose levels coming down.
On the other hand, if someone's starting A1c is below 8%, I might start by reducing their prandial insulin by 50% and maybe their basal insulin by 10%-20%, depending on their glucose levels. I think patients who are closer to target on insulin and/or a sulfonylurea agent are going to be at increased risk for going low.
Ideally, one can taper the patient off their insulin — and if not entirely off their insulin, off their prandial insulin — because it's much easier to give basal insulin and a once-weekly GLP-1 receptor agonist than to be on a multiple daily insulin regimen. Potentially, you'll be able to taper your patient off their insulin secretagogue as well.
The important thing to remember is that there's more than one moving target. You're uptitrating the GLP-1 receptor agonist or the GIP/GLP-1 receptor agonist and you're downtitrating the insulin secretagogue and/or the insulin. You want to downtitrate in gradual steps to keep ahead of any risk for hypoglycemia. Usually, that is done in slow steps, say, 10%-20% at a time.
It also means that you pay attention to your patients and that you may need to follow them every week or two, particularly if their A1c starts out below 8%, where they're likely to be at more risk for hypoglycemia.
If you pay attention to this process, you should be able to get your patient to a better point, hopefully on less medication that can cause hypoglycemia, and onto a medication that not only improves glucose but also helps with weight reduction, improves cardiovascular outcomes, and may have a renal benefit.
Thank you.
Anne L. Peters, MD, is a professor of medicine at the University of Southern California (USC) Keck School of Medicine and director of the USC clinical diabetes programs. She has published more than 200 articles, reviews, and abstracts, and three books, on diabetes, and has been an investigator for more than 40 research studies. She has spoken internationally at over 400 programs and serves on many committees of several professional organizations.
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Cite this: 'Moving Targets': Adjusting GLP-1 Agonists and Insulin - Medscape - Nov 08, 2023.
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