Why the sequence matters

Most preconception advice is general. For type 1 and type 2 diabetes it is not: NICE guideline NG3 sets out a defined programme of assessment and targets to complete before conception, because the organs most affected by glucose control in early pregnancy are forming in the first few weeks, often before a pregnancy is confirmed.

NICE's framing is worth quoting because it is neither alarmist nor falsely reassuring: good blood glucose control before conception and throughout pregnancy reduces the risk of miscarriage, congenital malformation, stillbirth and neonatal death, but the risks can be reduced, not eliminated.

This is also the reason NICE advises offering preconception care and advice before stopping contraception, and advises using contraception until blood glucose control is good. That instruction is unusual in fertility guidance and it is easy to hear as an obstacle. It is the opposite: it is the mechanism that lets the preparation actually happen.

The targets NICE sets

NICE recommends aiming to keep HbA1c below 48 mmol/mol (6.5%) before pregnancy, if that is achievable without causing problematic hypoglycaemia, and reassures that any reduction towards target is likely to reduce the risk of congenital malformation in the baby. That second half matters: this is a gradient, not a pass mark.

There is one firm threshold. NICE strongly advises people with diabetes whose HbA1c is above 86 mmol/mol (10%) not to get pregnant until it is lower, because of the associated risks.

For type 1 diabetes, NICE also gives capillary plasma glucose targets to aim for before pregnancy: a fasting level of 5 to 7 mmol/litre on waking, and 4 to 7 mmol/litre before meals at other times. Individualised targets are agreed with your team, taking the risk of hypoglycaemia into account. NICE recommends offering up to monthly HbA1c measurement while you are planning a pregnancy, meters for self-monitoring, and — for type 1 — blood ketone testing strips with advice to test if you become hyperglycaemic or unwell.

Medicines that change

This is the part most likely to be missed, and it is not something to adjust on your own. NICE recommends:

Stopping angiotensin-converting enzyme inhibitors and angiotensin-II receptor antagonists before conception, or as soon as pregnancy is confirmed, and using alternative blood pressure medicines suitable for pregnancy.
Stopping statins before pregnancy, or as soon as pregnancy is confirmed.
Stopping all oral blood glucose-lowering agents other than metformin before pregnancy, and using insulin instead. Metformin may be used as an adjunct or alternative to insulin in the preconception period and in pregnancy where the likely benefits outweigh potential harm.
Reviewing insulin regimens, glucose targets and monitoring before and during pregnancy.

Book this review deliberately rather than hoping it comes up. A medicines conversation is the difference between a planned switch and a rushed one at eight weeks.

Folic acid: a different recommendation from the general one

People with diabetes are one of the groups for whom a higher, prescription-strength dose of folic acid is recommended before conception and through the first 12 weeks, rather than the standard over-the-counter amount. The point of this page is not to name a number: the higher dose is a prescription, and getting it means asking your GP or diabetes team specifically, because it will not be dispensed by default and the standard supermarket product is not the same thing.

If you are also in another higher-dose group — for example a personal or family history of neural tube defects, or certain blood conditions or medicines — that reinforces the same action rather than changing it.

Eyes and kidneys, before you start trying

Two assessments NICE recommends specifically at the preconception stage, both easy to overlook because they do not feel related to fertility.

Retinal assessment

NICE recommends offering a retinal assessment at the first preconception appointment, unless one has been done in the last six months. It also gives an important practical instruction: defer rapid optimisation of blood glucose control until after retinal assessment and treatment. Bringing glucose down very quickly can worsen existing retinopathy, so the order of events matters.

Renal assessment

NICE recommends offering a renal assessment, including a measure of albuminuria, before stopping contraception, and considering referral to a nephrologist beforehand where serum creatinine is 120 micromol/litre or more, or where other thresholds set out in the guideline are met.

Weight, and how it is framed

NICE recommends offering individualised dietary advice, and offering advice on how to lose weight where BMI is above 27 kg/m², in line with its overweight and obesity guidance, which includes using variations on BMI cut-offs based on risk for different ethnic groups.

Two things are worth saying alongside that. Weight advice here is about pregnancy outcomes and glucose control, not about earning a pregnancy. And it does not replace the rest of the programme — nothing on this page is a substitute for the glucose, medicines, eye and kidney work, and no lifestyle change treats diabetes itself.

How to make it happen

NICE asks healthcare professionals to explain the benefits of preconception glucose control at every contact from adolescence onwards, and to record your plans for pregnancy. In practice, the appointment often has to be requested. Ask your diabetes team for a preconception review, and ask for it to cover: current HbA1c and target, monitoring, a full medicines review, folic acid, retinal assessment, renal assessment, and structured education if you have not attended a programme. NICE also recommends providing local support arrangements including emergency contact numbers, and encourages partners or family to attend.

If you have already conceived, none of this becomes irrelevant — it becomes urgent. Contact your diabetes team the same week rather than waiting for a routine antenatal appointment.

Trying to Conceive With Diabetes: What to Do First