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Pregnancy, breastfeeding and fertility while taking biphasic insulin - Brand names: Humalog Mix 25, Humalog Mix 50, Humulin M3, NovoMix 30

Biphasic insulin and pregnancy

You can take biphasic insulin while you're pregnant.

It's important that diabetes is well treated in pregnancy as regularly having blood glucose levels outside of your target range can be harmful for both you and your baby.

If you take insulin and are planning a pregnancy or become pregnant, it's important to speak to your doctor or community midwife. They'll help make sure your treatment is right for you and advise you on any changes to your dose that you may need during pregnancy.

You'll usually be seen in a specialist diabetes antenatal clinic, which will advise you on blood glucose monitoring, monitoring of your baby and your insulin dose.

It's common to need an increase in your insulin dose as pregnancy progresses.

Biphasic insulin and breastfeeding

You can take biphasic insulin while you're breastfeeding if you have type 1 or type 2 diabetes.

It's important that diabetes is well treated while breastfeeding as regularly having blood glucose levels outside of your target range can make it more difficult to get started with breastfeeding and can affect the amount of milk you make. Taking insulin can help with these problems.

You may need less insulin while breastfeeding than you did in pregnancy. Your doctor or diabetes nurse will help make sure your treatment is right for you and advise you on any changes to your dose that you may need while breastfeeding.

Each time you breastfeed you lose sugar through your breast milk, so your blood glucose level falls. Your diabetes nurse will talk to you about extra snacks you might need to help stop your blood glucose levels going too low and causing a hypo.

Insulin is naturally found in breast milk, and biphasic insulin will also pass into breast milk. Insulin is essential for the healthy development of your baby. The amount that passes across into breast milk is very unlikely to cause any unwanted effects in your baby.

If you notice that your baby is more sleepy than usual, seems paler than usual, sweaty or shaky, or if you have any other concerns about your baby, call 111 or talk to your doctor, pharmacist, health visitor or midwife as soon as possible.

Biphasic insulin and fertility

There's no evidence that biphasic insulin affects fertility in either men or women.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

Page last reviewed: 7 July 2023
Next review due: 7 July 2026