Insulin changes during pregnancy

Diabetes and pregnancy

The diabetes team talks to you about your ideal blood sugar levels when you are pregnant. In general, the targets for blood sugar levels during pregnancy are:

  • less than 5.3mmol/L before breakfast (fasting)
  • less than 7.8mmol/L 1 hour after each meal

Your insulin needs change constantly throughout pregnancy as your baby grows and hormones produced by the placenta start working. The placenta is an organ that connects your baby to the womb during pregnancy.

You need to be prepared to adjust your insulin doses every day or at least every week. It is important that you understand how each of your insulin works and affects the body. This helps you to adjust your doses effectively.

After your baby is born, your insulin needs return to the doses before you were pregnant. You may even need less insulin, especially if you are breastfeeding.

Actions to cope with insulin changes


  • record your insulin doses before you were pregnant. You can then refer to them immediately after the birth
  • record all your insulin pump settings before you were pregnant. You then have them to reset your pump immediately after the birth
  • record the name and dose of the diabetes tablets that you were taking before you were pregnant. This is useful in case you need to start the tablets again after the birth

Insulin changes in early pregnancy

Many people find it challenging to achieve their target blood sugar levels in the early stage of pregnancy. At this time, lots of changes are happening to your body and hormones.

If you have type 2 diabetes, we recommend that you talk about your medicine with the diabetes team. You may need to change your diabetes tablets and/or start insulin injections during pregnancy.

If you have type 1 diabetes, your insulin needs often decrease when you are between 6 and 16 weeks pregnant. This may cause severe hypos (episodes of low blood sugar), sometimes without warning. 

Preventing a hypo is better than treating one. An important tip is not to miss any meals or snacks. It is essential that you make a habit of carrying treatment for a hypo with you at all times. For example, if you carry glucose tablets or jelly babies and a carbohydrate snack like dry biscuits, you can treat a hypo quickly.

Actions to manage hypos during early pregnancy


  • check that you have a GlucaGen® HypoKit® (a prescription emergency kit to treat very low blood sugar). Make sure that the kit is in date and that your partner or anyone who lives with you knows how to use it
  • carry treatment for a hypo, such as glucose tablets or jelly babies and dry biscuits, with you at all times
  • keep regular (non-diet) soft drinks and dry biscuits by your bed
  • make a plan with your diabetes team that covers the times and number of blood sugar tests you do each day or week

Insulin changes in mid-pregnancy

Your insulin needs start to increase from when you are 20 weeks pregnant. Eventually, you may need 2 or 3 times the amount of insulin that you had before you were pregnant.

Hormones produced by the placenta interfere with how your insulin usually works and direct food to your baby. You need more insulin because this allows food to pass into your own body cells.

Insulin changes at birth

When your baby is born, your insulin needs return to normal after you have delivered the placenta.

Breastfeeding may reduce your insulin needs again. We have more information about this.

Resource number: 1702/VER4
Last reviewed: September 2022
Next review due: September 2025

A list of sources is available on request.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

Is this health information page useful?