Diabetes before and during pregnancy — Rapid

Synopsis

Manage pre-existing and gestational diabetes across conception, antenatal surveillance, birth and postpartum care while preventing hypoglycaemia, ketoacidosis and avoidable fetal complications.

Before conception aim for HbA1c below 48 mmol/mol if achievable without problematic hypoglycaemia and prescribe folic acid 5 mg daily through 12 weeks.
Screen defined risk groups using a 75 g two-hour OGTT; NICE gestational-diabetes thresholds are fasting at least 5.6 mmol/L or two-hour at least 7.8 mmol/L.
During pregnancy aim for fasting glucose below 5.3, one-hour post-meal below 7.8 or two-hour below 6.4 mmol/L, while keeping insulin-treated glucose above 4 mmol/L.
Offer a joint diabetes–antenatal appointment within one week of gestational-diabetes diagnosis and regular contact throughout pregnancy.
When diagnostic fasting glucose is below 7 mmol/L, trial diet and exercise; add metformin if targets remain unmet after one to two weeks, or insulin when metformin is unsuitable.
Fasting glucose at least 7 mmol/L at diagnosis requires immediate insulin, with or without metformin; consider this also at 6.0–6.9 with macrosomia or hydramnios.
Offer real-time CGM for type 1 diabetes and assess eligibility for hybrid closed-loop treatment through an experienced team.
After gestational diabetes stop glucose-lowering therapy at birth, check for persistent hyperglycaemia and arrange fasting glucose at six to thirteen weeks plus annual surveillance.

Key red flags

Vomiting, abdominal pain, tachypnoea, dehydration or drowsiness with diabetes requires urgent ketone assessment even when glucose is only modestly elevated.

Severe hypoglycaemia, impaired awareness or inability to retain essential insulin-related carbohydrate requires prompt treatment and specialist advice.

Reduced fetal movements or a sudden unexplained fall in insulin requirements warrants maternity assessment rather than self-directed dose changes alone.

Investigation priorities

75 g two-hour oral glucose tolerance testFirst step

Diagnose gestational diabetes in the appropriate screening population.

Management branches

PreconceptionReduce early-pregnancy risk before conception

Someone with type 1 or type 2 diabetes is planning pregnancy.

Review HbA1c, retinal and renal status, hypoglycaemia history, medicines and the preferred timing of conception.
Prescribe 5 mg folic acid daily and optimise glucose safely with specialist support before stopping contraception when possible.
Provide ketone equipment and sick-day advice for type 1 diabetes, and ensure the patient can access urgent diabetes and maternity help.

Key medicines

Metformin with a gradual introductionA commonly used NHS pregnancy regimen starts at 500 mg orally with the evening meal, then increases gradually according to tolerance and glucose response; document the formulation and prescribed maximum, often 1 g twice daily.Review renal function, dehydration, hypoxia and gastrointestinal tolerance; withhold during acute illness that increases lactic-acidosis risk and check the selected product's current pregnancy authorisation.

Subcutaneous insulinPrescribe an individual basal and/or mealtime subcutaneous regimen with doses in units, exact insulin products and a written titration algorithm based on fasting and post-meal readings; continue until the planned post-birth reduction or cessation.Prevent insulin omission, product confusion and hypoglycaemia; supplies and device training are essential, and renal impairment or postpartum changes can reduce requirements.

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