Diabetes Medications During Pregnancy: Insulin vs. Oral Options Explained

Managing Diabetes in Pregnancy Isn’t One-Size-Fits-All

When you’re pregnant and have diabetes-whether it was there before you got pregnant or developed during pregnancy-your body changes in ways that make blood sugar control harder. Hormones from the placenta fight against insulin, making you more resistant to it. That means even if your blood sugar was stable before, it can spike quickly once you’re pregnant. The goal isn’t just to feel better; it’s to protect your baby from risks like being born too large, having low blood sugar after birth, or even developing long-term metabolic problems. And that’s where choosing the right medication becomes critical.

Insulin Is Still the Gold Standard

For decades, insulin has been the go-to treatment for diabetes in pregnancy, and it still is. Why? Because it doesn’t cross the placenta. That means your baby isn’t exposed to the drug itself-only to the effects of your blood sugar levels. This makes insulin the safest option when you need medication to keep glucose in check.

Not all insulins are created equal. Rapid-acting analogs like insulin lispro and insulin aspart are preferred over regular human insulin because they work faster and clear out quicker after meals. That helps you hit those tight targets: fasting blood sugar under 95 mg/dL, and under 120 mg/dL two hours after eating. Long-acting insulin options like detemir and NPH have been studied in thousands of pregnant women and show similar safety profiles. But insulin glulisine and degludec? They’re not recommended yet. There’s just not enough data.

Some women use insulin pumps (continuous subcutaneous insulin infusion). Studies show they can lead to slightly lower HbA1c levels and less insulin needed near delivery. But here’s the catch: babies born to moms using pumps don’t have better outcomes than those whose moms use multiple daily injections. So if you’re comfortable with shots, you’re not missing out on safety.

Metformin: A Controversial Alternative

Metformin is an oral pill commonly used for type 2 diabetes and gestational diabetes outside of pregnancy. During pregnancy, it’s a gray area. Some studies show it lowers the risk of having a very large baby, reduces NICU admissions, and cuts down on preeclampsia compared to insulin. In fact, one large analysis found women on metformin had a 35% lower chance of having a large-for-gestational-age baby.

But here’s the problem: metformin crosses the placenta. That means your baby is exposed to the drug. We don’t fully understand what that means long-term. Some animal studies suggest it might affect the mTOR pathway-a key system involved in fetal growth and metabolism. And about half of women who start metformin during pregnancy end up needing insulin anyway because their blood sugar stays too high.

Guidelines are split. The Endocrine Society says don’t add metformin to insulin if you already have type 2 diabetes. The Joslin Diabetes Center says don’t use it beyond the first trimester. But other groups, like those behind the NIH meta-analysis, see enough benefit to recommend it as a first-line option for gestational diabetes. The bottom line? If you’re considering metformin, talk to your doctor about your personal risks and whether you’re willing to switch to insulin if it doesn’t work.

What About Other Oral Medications?

There are plenty of diabetes pills on the market, but almost none are safe in pregnancy. GLP-1 receptor agonists like semaglutide and liraglutide? Stop them before you even try to get pregnant. They’re linked to fetal risks in animal studies, and we simply don’t know enough about their effects in humans. Same goes for SGLT2 inhibitors like dapagliflozin and empagliflozin. These drugs make your kidneys flush out sugar, but they can also cause dehydration and low blood pressure-both dangerous during pregnancy.

DPP-4 inhibitors (like sitagliptin) and alpha-glucosidase inhibitors (like acarbose)? No solid safety data. Not recommended. The truth is, outside of insulin and metformin, your options are extremely limited. That’s why many doctors feel stuck. They want to help you avoid insulin injections, but they can’t justify using drugs with unknown risks.

Preconception Planning Matters More Than You Think

If you have type 1 or type 2 diabetes and are thinking about getting pregnant, waiting until you’re already pregnant to start managing your blood sugar is risky. The first eight weeks of pregnancy are when your baby’s organs form. High blood sugar during that time increases the chance of birth defects by up to 10 times.

Experts recommend getting your HbA1c below 6.5% before conception. If it’s above 10%, most clinics will strongly advise against pregnancy until your numbers improve. That might mean switching medications, adjusting your diet, or using a long-acting birth control method while you get your diabetes under control. One clinic in Oregon even recommends offering IUDs or implants to women with very high HbA1c levels-because the goal isn’t to stop you from having kids, but to make sure you’re healthy enough to carry them safely.

What Happens During Labor and After Delivery?

During labor, your blood sugar can swing wildly. That’s why hospitals monitor it hourly. If it goes too high, you might get IV insulin. If it drops too low, you’ll get glucose drips. It’s intense, but it’s standard. Most women who use insulin pumps can keep them on during labor, as long as the medical team knows how to manage them.

After delivery, things change fast. The placenta is gone, so insulin resistance drops sharply. Many women who needed insulin during pregnancy can stop it right after birth. The same goes for metformin. If you had gestational diabetes, you’ll likely be tested again 6 to 12 weeks postpartum to see if your diabetes resolved-or if you’ve developed type 2 diabetes. About half of women with gestational diabetes will go on to develop type 2 within 10 years. That’s why follow-up care isn’t optional.

Monitoring: CGM vs. Finger Sticks

Continuous glucose monitors (CGMs) are becoming more common. They give you real-time readings and show trends-something finger sticks can’t do. For women with type 1 diabetes, studies show CGMs lead to better baby outcomes. But for type 2 or gestational diabetes? The evidence isn’t clear yet. The Endocrine Society says we don’t have direct proof that CGMs are better than checking your blood sugar four times a day with a meter. Still, if you’re struggling to hit targets, a CGM might help you see patterns you’re missing.

Aspirin Isn’t Just for Heart Health

Here’s something most people don’t know: low-dose aspirin (81-100 mg daily) is routinely recommended for pregnant women with preexisting diabetes. It’s not to prevent heart attacks-it’s to reduce the risk of preeclampsia, a dangerous condition that can cause high blood pressure, organ damage, and early delivery. Guidelines from ACOG, Joslin, and OHSU all agree: start it at 12 weeks and keep going until delivery.

What’s Next? The Big Unknowns

We’ve come a long way in reducing birth defects and stillbirths in diabetic pregnancies. But we still don’t know the full impact of medications on a child’s long-term health. Does in-utero metformin exposure change how a child’s body processes sugar later in life? Could insulin analogs affect brain development? These are open questions. Researchers are tracking children born to mothers who used these drugs during pregnancy, but results will take decades.

For now, the safest path is clear: aim for tight control before pregnancy, use insulin when you need it, avoid unproven oral meds, and don’t skip follow-ups after birth. You’re not just managing your diabetes-you’re shaping your child’s future.