Insulin or metformin are the preferred choices during breastfeeding. 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, or metformin can be used in breastfeeding. There is limited or no published information on the use of other antidiabetic (blood-glucose lowering) medicines during breastfeeding. Contact us for advice about other antidiabetic medicines, or about using them for indications other than diabetes.

Management of diabetes

Insulin requirements may be less, and dosages of antidiabetic medicines may be different, 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.

Specific recommendations

Patient information

Patient information for insulins and other antidiabetic medicines is available from the NHS Website: Medicines A-Z, including their use in breastfeeding.

Further advice

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

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

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principles, extrapolation from similar drugs, risk assessment of normal clinical use, expert advice, and unpublished data.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 are now increasingly being used due to the ethical difficulties around gathering good quality evidence in this area.


Full referencing is available on request.

Update history

  1. Updated to include advice on metformin, and other antidiabetic medicines
  1. Published

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