Preconception care in women with known pre-existing diabetes

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The British National Formulary (BNF) indicates that glucagon-like peptide 1 agonists (GLP-1), dipeptidyl peptidase-4 (DPP-4) inhibitors, thiazolidinediones and sodium glucose cotransporter 2 (SGLT2) inhibitors should be avoided in pregnancy for reasons ranging from lack of information on their effects to toxicity in animal studies. Sulphonylureas should be avoided in pregnancy due to risk of neonatal hypoglycaemia. Glibenclamide was previously used in pregnancy but the adult formulation has been withdrawn.

Blood glucose levels should be optimised when women with diabetes are planning pregnancy. To facilitate this, opportunistic conversation should be initiated during every annual review with women of childbearing age, including consideration of use of insulin pumps and CGM to optimise individual glucose levels. Body mass index should be reviewed and weight management advice offered if appropriate. Other lifestyle factors should be discussed such as contraception, healthy eating and exercise, stopping smoking and avoiding alcohol and other drugs.

Glycaemic targets when planning a pregnancy

Although a goal of <48 mmol/mol is desirable, there appears to be a linear relationship between HbA1c level and adverse perinatal outcomes suggesting that any reduction in prepregnancy HbA1c while avoiding excessive hypoglycaemia is likely to be beneficial.

Women with type 1 diabetes (T1DM) or type 2 diabetes (T2DM) planning a pregnancy should aim for an HbA1c as low as possible without excessive hypoglycaemia.

Women should be offered advice on weight management prior to pregnancy in line with guidance from the Royal College of Obstetricians and Gynaecologists and national programmes (for example, A Healthier Future: type 2 diabetes prevention, early detection and intervention framework). This is likely to be of particular benefit to women with type 2 diabetes or prior GDM when planning pregnancy

Advise women that HbA1c <48 mmol/mol can minimise risk of perinatal mortality and morbidity but should not be used a strict threshold for access to assisted conception services. An individualised approach should be used.

Other risk factors such as body mass index (BMI), smoking, hypertension and level of diabetic retinopathy should be taken into account when individualised HbA1c targets are being considered.

Pregnancy should be avoided if HbA1c >86 mmol/mol.

Referral of women with T2DM who are planning a pregnancy to secondary care for optimisation of their diabetes should be considered, including the possibility of the use of CGM if preconception glycaemic targets are not being met. If not already being used, this is an opportunity to further consider medication to lower cardiovascular risk.

Diabetes and obstetric teams should take opportunities to engage with all women with pre-existing diabetes early in pregnancy irrespective of their attendance at prepregnancy counselling clinics. This should be as soon as possible after a positive pregnancy test, ie before the formal ‘booking’ appointment takes place.

All medications should be reviewed prepregnancy for suitability in pregnancy and women should be advised to take 5 mg folic acid for at least 3 months prior to conception and throughout the first trimester.