Glycemic Response to Overnight Breastfeeding With Open- vs Closed-Loop Among Patients With Type 1 Diabetes

In this podcast, Lois E. Donovan, MD, and her team from the University of Calgary set out to determine the relationship between breastfeeding episodes and maternal glucose levels, as well as whether glucose levels change depending on either closed loop or open loop insulin therapy.

Additional Resources: Donovan LE, Bell RC, Feig DS, et al. Glycaemic patterns during breastfeeding with postpartum use of closed-loop insulin delivery in women with type 1 diabetes. Diabetologia. 2024;67(10):2154-2159. doi:10.1007/s00125-024-06227-z

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TRANSCRIPTION

Anthony Calabro, MA: Hello everyone, and welcome to another installment of Podcast360, your go-to resource for medical education and clinical updates. I'm your moderator, Anthony Calabro with Consultant360, a multidisciplinary medical information network. Although breastfeeding is recommended for women with diabetes, they are less likely to breastfeed than those without diabetes. Why is this? There are several factors in play, including concern with potential postpartum hypoglycemia following breastfeeding. To better understand this concern, Dr. Lois E. Donovan and her team from the University of Calgary set out to determine the relationship between breastfeeding episodes and maternal glucose levels, as well as whether glucose levels change depending on either closed loop or open loop insulin therapy. Thank you, Dr. Donovan for joining us today. My first question is a simple one. What brought about this study?

Lois E. Donovan, MD: As a clinician who works in the area of diabetes and pregnancy, women ask me a lot of questions, and sometimes I have the answers and I can answer them and sometimes I don't. And that's what really inspires my research. [My goal] is to try to get some of the answers to the questions that we're lacking that people would really like some information on. So specifically, for this question that we asked women, when they've got, understandably when they've got a newborn and they've got diabetes, they are quite fearful of hypoglycemia, particularly hypoglycemia that would render them incapable or at least make it challenging for them to care for their newborn, which is not surprising at all. And I can say personally as a mom, there's so many changes that come with being a new mom. And then when you add diabetes on top of that, it's a particularly challenging time to manage diabetes because much of managing diabetes are things that you've learned about what you need to do to adjust your insulin for a certain schedule. Well, any new mom knows that your schedule is out the window with a baby. And so managing diabetes can be particularly challenging. And one of the concerns that women have expressed to me, and I know that women have talked among women living with type 1 diabetes, have talked about their concerns with having hypoglycemia postpartum, particularly if breastfeeding contributes to that. And I know that there's some concern that women feel like it is a contributor to hypoglycemia, but really what's the evidence behind that? So we wanted to look at that, and we also wanted to see how automated insulin delivery influenced that, because this is, as you know, there's really a paradigm shift going on in the management of type 1 diabetes with increasing use of automated insulin delivery. And could this potentially even be a tool that would aid women postpartum who are breastfeeding in preventing hypoglycemia or at least making them less fearful of hypoglycemia with breastfeeding? Because I've actually seen some unfortunate circumstances where women are reluctant to even start breastfeeding, or they finish breastfeeding sooner than they anticipate or wanted to because of their fear of hypoglycemia. And is that something that's just being perpetuated or is that really real or is it real for some individuals but not others? So we wanted to delve into that some more.

Anthony Calabro: What were the results and the main takeaways from your study?

Dr Donovan: So it was really interesting because we found most of the time breastfeeding was not accompanied by hypoglycemia. And that over 93% of the time, breastfeeding episodes, women did not have hypoglycemia within a few hours that followed that. The other thing we found that yes, there is a drop in blood sugar with breastfeeding, but the lowest point is only about, well, it comes about two hours after breastfeeding, not immediately after breastfeeding. So there was a decline in glucose. But the other thing we found is that decline was really small. So when people were not using automated insulin delivery, that decline on average was 1.2 Mmmol/L. So if you're talking milligrams per deciliter, what is that? A drop of about 22 mg/dL in the first 2 hours after breastfeeding. Now with closed loop, we found that that drop was only 0.4 mmol/L, so that would be closer to 7.2 mg/dL. So unless a woman is already running a low blood sugar or blood sugar less than 4 mmol/L, so less than 72 mg/dL, the drop that they may see with breastfeeding is unlikely to be clinically relevant for them. And I think that's an important message to get out there. Now, I recognize our study was small and it will be important to repeat such a larger study that's more inclusive of individuals. We first started collecting this information at four weeks postpartum too, so it may be that there's greater struggles earlier, so that would be an important thing to look at. But I think it's quite reassuring. And I think the other thing that has come out of this study, as was indicated in some earlier work, was that if you have proper adjustment of insulin for the postpartum period, that is probably more important than being concerned that you're going to have dangerous drops in low blood sugar with breastfeed. And it's true, the adjustments that you have to make to insulin dosing from pregnancy to postpartum are substantial. And I've been fortunate to do some qualitative work in this space, and I'll admit, I thought I knew what was going on until I actually did this work. I think I talk to these women, this is what I do all day long. I see people but learn some new things just about how fearful they are of breastfeeding, dropping and dropping their blood sugars. But I also learned, I used to follow people up six weeks postpartum because as a new mom, I thought, wait a minute, when you've got a baby, you're busy. You don't have time for medical appointments. And that's what I thought. I don't live with type 1 diabetes. I thought, don't bug me. I don't want to talk to anybody. I've got a new baby to take care of. What we heard was that actually this, these women felt somewhat abandoned and that they wanted follow up soon after they had their baby. And so now, as part of my routine care of women with type 1 diabetes postpartum, I schedule a phone follow up with them within a week of their delivery. They get help in hospital, but once they're home caring for that baby, they really appreciate that one week postpartum visit by phone. And that's something I learned from the qualitative interviewing. And so I think that's a really important opportunity to make sure that the insulin has been adjusted for postpartum. And that's my point is if insulin's been adjusted appropriately for the postpartum period, this study supports the fact that we don't have to be very anxious about hypoglycemia occurring with breastfeeding.

Anthony Calabro: How early are you having these discussions about managing their diabetes postpartum?

Dr Donovan: Well, I guess it's an important part of pregnancy care is planning for postpartum because it's not uncommon for women with type 1 diabetes to have to have an early delivery or to have complications, high blood pressure complications that might require an urgent or emergent delivery. And so I'm talking to women about how they will manage things postpartum sometimes as early as 24 or 28 weeks of gestation and not leaving it so that it's not done. It is just too important and has to be done.

Anthony Calabro: What are the gaps in our knowledge that still remain? What is it that we still need to know and how do we go about filling those gaps?

Dr Donovan: So we looked at postpartum women. That's a very understudied time in women's lives that we need information, right? But we also, pregnancy is also an understudied area of time. Often people want to who do clinical trials where they want to take that population out so they don't have to worry about them, but we need to know how things behave in pregnancy. So an area that needs to be addressed is the use of these automated insulin delivery systems in pregnancy. Now, Professor Helen Murphy in the UK, has already done some fantastic work in that area over many, many, many years, and shown benefits to the system that she helped to develop to ensure that it was good for pregnancy. That's the CamA PS or Cambridge APS system. But that's not yet available to us in Canada. And although it's been approved for use in the US, I'm not sure about the availability in the US yet either. I know it's coming, but as a result, we know that women are getting pregnant on commercial automated insulin delivery systems, and there's a question about whether we can maintain those safely during pregnancy or not. And if the woman and her care providers choose to do that, what is the best way to optimize those systems? So that's an area that there's a gap in, and there's ongoing research in that area. And I'm fortunate to be co-leading a study called the CIRCUIT Trial that is looking at one of those commercial automated insulin delivery systems, and we hope to have results by summer.

Anthony Calabro: That leads into my next question. What are you working on next?

Dr Donovan: That's correct. But I also want to highlight another interesting spinoff from the study that we're talking about. Once again, getting back to the fact that many of my research questions come from clinical questions that women ask me and I want to get the answers for. And one question that I often get asked by women is: okay, so I'm breastfeeding, do I have to worry about what my blood sugar is at the time of breastfeeding? And that's a really interesting question. And I used to say, oh, no, don't worry about that. The baby will just, there's more glucose in your breast milk, then they'll just take less. So don't worry about it. But I really had to stop myself and think, wait a minute, do I know about what, does the literature say? And it was a huge gap there, and I thought, women want to know this answer, and I get it. So I'm very grateful to the women that participated in this study that we're talking about because many of the breastfeeding moms in the study, they collected breast milk samples. And so we have analyzed the breast milk for content, and they also did some weighing of their child before and after they breastfed for us to get an idea of how much breast milk they took in. So we're currently analyzing those results and hope to get that written up and published soon.

Anthony Calabro: I can't imagine taking care of a newborn while also noting all of these details in a research study.

Dr Donovan: Hats off managing a newborn is a huge job to begin with. And then you add diabetes and the challenges of a new routine to that. And then you add participating in a research study and collecting breast milk and writing down when you were breastfeeding. It was a lot, and I'm really, really grateful. But the women did it quite altruistically. They wanted to know the answers and they wanted to help other women who live with type 1 diabetes. So I'm very grateful to them for participating.