New international clinical guidelines push for the best preconception care to reduce problems during pregnancy.
All women with diabetes should be asked about their intent to conceive at every visit, according to new international clinical guidelines.
“We developed these guidelines as diabetes rates are rising among women of reproductive age and very few women with diabetes receive proper preconception care,” US endocrinologist and guideline chair Clinical Professor Jennifer Wyckoff told press.
“In addition to preconception planning, the guideline discusses advances in diabetes technology, delivery timing, medications and diet.”
The guideline, jointly written by the Endocrine Society and European Society of Endocrinology, recommended pregnant women deliver before week 39 as the risks of continuing the pregnancy may outweigh the potential harms of the earlier delivery.
It also advised women to stop their GLP-1 medications prior to becoming pregnant, and for GPs to avoid prescribing metformin to those who were already pregnant who had pre-existing diabetes and were already on insulin.
GPs can also recommend hybrid closed loop systems for pregnant people with type 1 diabetes, it said.
It also suggested contraception should be used by women with diabetes until they were ready to be pregnant.
The guideline authors said the advice to screen patients about pregnancy intention at every visit came from indirect evidence strongly linking preconception care with lower HbA1c at the first prenatal visit as well as congenital malformations.
There was some limited data to suggest stopping GLP-1 receptor agonists before conception was safer than stopping some time in the first trimester.
“In pregnant individuals with T2DM already on insulin, we suggest against routine addition of metformin,” the guideline said.
“This was suggested based on the Guideline Development Panel judgment that the benefit of adding metformin to insulin to achieve decrease in rates of large for gestational age infants did not outweigh the potential harm of increasing the risk of small for gestational age infants or adverse childhood outcomes related to changes in body composition.”
Patients with pre-existing diabetes are recommended to either have a carbohydrate-restricted diet (<175g/day) or usual diet (>175g/day) during pregnancy, due to substantial uncertainty in the literature about overall benefits and harms of carbohydrate-restricted diet.
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The authors said there wasn’t direct evidence supporting the use of a continuous glucose monitor (CGM) over self-monitoring of blood glucose in patients with type 2 diabetes for pregnancy, but indirect evidence showed better glucose control with continuous glucose monitors outside of pregnancy. There was also evidence supporting better neonatal outcomes in women with type 1 diabetes who used the devices.
“In individuals with pre-existing diabetes mellitus using a CGM, we suggest against the use of a single 24-hour CGM target <140mg/dL (7.8mmol/L) in place of standard-of-care pregnancy glucose targets of fasting <95mg/dL (5.3mmol/L), 1-hour postprandial <140mg/dL (7.8mmol/L), and 2-hour postprandial < 120mg/dL (6.7mmol/L),” the guideline said.
“This was suggested based on indirect evidence that associated adverse pregnancy outcomes with a fasting glucose > 126mg/dL (7mmol/L).”
The authors also said that postpartum endocrine care should be added to usual obstetric care for those with pre-existing diabetes, including those who had a pregnancy loss or termination.
Ultimately, the data supporting these recommendations was of low or very low certainty, the authors said, emphasising the need for better research into the relationship between diabetes interventions and pregnancy.
Dr Gary Deed, chair of the College’s Specific Interests Diabetes group, noted that Australia’s advice on metformin was more specific and included guidance on GLP-1 receptor agonists.
The College said metformin was not tied to a rise in congenital malformation or early pregnancy loss, although it remained a category C drug in pregnancy.
“[Metformin] could be used as an adjunct to other therapies, including insulin, in type 2 diabetes, both before conception and during pregnancy. Consult with specialist endocrine and obstetric services,” it said.
GLP-1RA and GIP/GLP-1RA drugs were listed as a category D, and doctors were advised to review or stop the medication and to start insulin therapy instead.
The recommendations did not include advice on how to use diabetes technologies for patients with type 1 diabetes in pregnancy.
The Journal of Clinical Endocrinology & Metabolism, online 13 July 2025
This article was updated to include comments from Dr Deed and RACGP recommendations.