Guidance on continuing or initiating insulins in breastfeeding mothers. Recommendations apply to full term and healthy infants only.

General considerations

It is important to complete an individual risk assessment for your patient and to apply the principles of prescribing in breastfeeding when looking at the available information and making treatment decisions.


All insulins can be used in breastfeeding.

Further information

Insulin is naturally found in breast milk and is essential for the healthy development of the infant. A small amount is absorbed by the infant and helps with intestinal maturation and induces glucose tolerance. It may also decrease the risk of developing type 1 diabetes.

Exogenous insulin is also excreted into breast milk, including that from insulin analogues. The amount that passes across into milk is unlikely to cause any side-effects in the breastfed infant. The majority of exogenous insulin will be destroyed in the infant’s gastro-intestinal tract and will not be absorbed.

Insulin requirements

Insulin requirements may be less than those needed during or before pregnancy since glucose is being used for milk production.

Effect on breastfeeding

It is important that diabetes is well treated while breastfeeding. Poorly controlled blood sugar levels can make it more difficult to get started with breastfeeding and can affect the amount of milk produced.

Infant monitoring

As a precaution, monitor the infant for signs of hypoglycaemia, including drowsiness, appearing pale, or being sweaty or shaky.

Patient Information

The NHS website provides advice for patients on the use of insulins in breastfeeding.

Contact us

Get in touch with the UK Drugs In Lactation Advisory Service (UKDILAS), our specialist breastfeeding medicines advice service if you need support in the following situations:

  • you need further advice
  • the medicine in question is not included in our advice
  • the infant is unwell or premature
  • multiple medicines are being taken

About our recommendations

Recommendations are based on published evidence where available. However, evidence is generally very poor and limited, and can require professional interpretation. Assessments are often based on reviewing case reports which can be conflicting and lack detail.

If there is no published clinical evidence, assessments are based on: pharmacodynamic and pharmacokinetic principles, extrapolation from similar drugs, risk assessment of normal clinical use, expert advice, and unpublished data. Simulated data is now increasingly being used due to the ethical difficulties around gathering good quality evidence in this area.


Full referencing is available on request.