If you have diabetes in pregnancy, you may have been reading about a debate concerning the medications that we use to treat it. Before we talk about the controversy, let me tell you a little about these medications:
- Insulin – Insulin has been used to treat diabetes since the 1920’s, so we know a lot about how it works. We also know that it’s considered safe in pregnancy. It does not cross the placenta, so no insulin passes to the fetus. There are many types of insulin – long-acting, intermediate, and short-acting. So we can adjust doses to target elevated blood glucoses at particular times of the day or after particular meals.
- Metformin – Metformin is an oral medication used to treat diabetes. It reduces the amount of glucose that is absorbed and released from your liver, and it increases insulin sensitivity – that means it helps glucose get into your cells to provide energy. Metformin also decreases intestinal absorption of carbohydrates. This leads to the most common side effect reported with metformin – a little cramping and diarrhea. So we try to start at a low dose and ask you to take it with food. Metformin does cross the placenta, and it has been detected in babies’ bloodstream after delivery. Is this bad? We don’t think so, but long-term studies are still being performed. Metformin doesn’t always do an adequate job of controlling glucoses, and almost half of women who are placed on metformin in pregnancy will need to start insulin before they deliver their babies.
- Glyburide – Glyburide is a sulfonylurea drug. This means that if you have a sulfa allergy, you will probably not be able to take this medicine. Glyburide works by stimulating your body to release more insulin. This means that timing is important for taking glyburide. You have to take it before a meal; if you take it without eating, your blood glucose may drop lower than we want it to. Some women taking glyburide will need to switch to insulin if glucoses are not well-controlled.
Now to the nitty-gritty. The American College of Obstetricians and Gynecologists issued a statement in February 2018 recommending insulin as the primary drug to treat diabetes in pregnancy. They cited safety concerns for moms and babies taking oral medications and stated that these medications are not FDA-approved for use in pregnancy. The Society for Maternal-Fetal Medicine issued their own statement in response to the ACOG recommendation. The SMFM questioned ACOG’s reasoning, stating that no new evidence had emerged to justify ACOG’s change in recommendation. SMFM pointed out that patients have a strong preference for oral medications, which are easier to take and generally less expensive. The SMFM concluded that oral medications are a safe and reasonable alternative to insulin in some pregnant women. Then some MFM physicians waded into the fray. They published an editorial of their own in the American Journal of Ob/Gyn, saying that the SMFM should not be so hasty in recommending oral agents in pregnancy. These physicians said that we can’t be certain that metformin is a good alternative to insulin since metformin can act on fetuses at the cellular level. We just don’t know the long-term metabolic effects on these kids yet.
So where does this debate leave us? The takeaway seems to be this:
- For pregnant women whose blood glucoses are not well-controlled with diet and exercise alone, insulin is probably the best choice when medication is required. We should use the lowest dose needed, and try to target the specific glucoses that are abnormal. For instance, if your glucoses are only elevated after lunch, then you can take a single dose of short-acting insulin before lunch. (If you and your provider are really motivated, you can experiment with dividing that lunch into two smaller, protein-packed meals and see if that helps, before starting medication.)
- If you are unable or truly unwilling to take insulin (due to fear of needles, inconvenience, expense, scheduling, etc), then metformin is a reasonable alternative.
- Glyburide generally gets a thumbs-down unless there is no alternative because published studies show that outcomes for babies may not be as good. There appears to be a higher incidence of bigger babies and low blood sugars in newborns.
I hope this helps to demystify the ongoing debate about medications for diabetes in pregnancy. If you have diabetes and you are at the point of needing to start medication, talk to your provider about options. You may feel that you can get control of your glucoses if given more time to work with your diet. This may be true if your blood sugars are just a little elevated, or are elevated only at a certain time of day. But remember that time is limited in pregnancy, and every day that your glucoses are elevated, your baby is affected. Don’t be reluctant to start medication if it’s needed. Also remember that if you start medication, this does not give you a green light to eat badly. No medication takes the place of eating well and staying active. As always, contact me with questions and comments, and talk to your provider, who knows the specifics of your individual care. Good luck, you’ve got this!