Type 2 Diabetes in Pregnancy

You are on the pre-existing diabetes pathway

If you had type 2 diabetes before you conceived, NICE guideline NG3 treats you under its pre-existing diabetes recommendations, not the gestational diabetes ones. That matters because the two sets of numbers differ, most obviously the week your birth is planned for. Search results mix them constantly.

Type 2 diabetes is also increasingly diagnosed for the first time in early pregnancy. NG3 recommendation 1.3.10 asks for HbA1c to be measured when gestational diabetes is diagnosed precisely "to identify women who may have pre-existing type 2 diabetes". If that is how you found out, your care moves onto this pathway rather than the gestational one.

Your tablets: what stops, what stays

This is the first thing that changes, and it usually changes before conception rather than after.

NICE NG3 recommendation 1.1.21: women with diabetes "may be advised to use metformin as an adjunct or alternative to insulin in the preconception period and during pregnancy, when the likely benefits from improved blood glucose control outweigh the potential for harm. Stop all other oral blood glucose-lowering agents before pregnancy, and use insulin instead."

So metformin is the exception, not the rule. Gliclazide, SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors and the rest are stopped and replaced with insulin. This page names those medicines and does not give doses; that belongs to the clinician making the switch.

On insulin choice, NG3 recommendation 1.1.23 names isophane insulin, also called NPH, as the first choice for long-acting insulin during pregnancy, while allowing long-acting analogues to continue for women who already had good control on them. Recommendation 1.1.22 notes that the available evidence on the rapid-acting analogues aspart and lispro does not show an adverse effect on the pregnancy or the baby.

Medicines for the complications of diabetes are reviewed too. Several classes of blood pressure tablet and statins are stopped or swapped before or as soon as pregnancy is confirmed, so bring every box to your first appointment rather than only the diabetes ones.

The numbers

Before pregnancy, NG3 recommendation 1.1.18 asks you to aim for an HbA1c below 48 mmol/mol (6.5%) if that is achievable without problematic hypoglycaemia, and recommendation 1.1.20 strongly advises against conceiving with an HbA1c above 86 mmol/mol (10%). Recommendation 1.3.7 measures HbA1c at booking to grade risk, and 1.3.11 says not to use it routinely as a control measure later in pregnancy.

Day to day, recommendation 1.3.5 asks for capillary plasma glucose below 5.3 mmol/litre fasting, and either below 7.8 mmol/litre one hour after meals or below 6.4 mmol/litre two hours after meals. If you are on insulin, recommendation 1.3.6 asks you to stay above 4 mmol/litre.

Real-time continuous glucose monitoring is offered to everyone with type 1 diabetes. For type 2, NG3 recommendation 1.3.18 is narrower: consider it for pregnant women on insulin therapy who do not have type 1 diabetes if specific circumstances apply, such as problematic severe hypoglycaemia or unstable glucose levels. Ask; do not assume.

Extra appointments, scans and checks

You will be offered a joint diabetes and antenatal clinic. Retinal assessment is offered after your first antenatal appointment unless you have had one in the last 3 months, with an extra assessment at 16 to 20 weeks if you already have retinopathy, and another at 28 weeks. A renal assessment is offered if you have not had one in the last 3 months.

For the baby, NG3 asks for a 20-week scan that specifically examines the fetal heart in four chambers, outflow tracts and three vessels, then growth and amniotic fluid scans every 4 weeks from 28 to 36 weeks. NG3 recommendation 1.3.35 explicitly says routine fetal wellbeing monitoring before 38 weeks, including Doppler and biophysical profile, is not recommended unless there is a risk of growth restriction. If you are told you do not need weekly monitoring, that is guideline-concordant care rather than neglect.

The birth window

NICE NG3 recommendation 1.4.2: elective birth by induced labour or caesarean if indicated, "between 37 weeks and 38 weeks plus 6 days of pregnancy", for type 1 or type 2 diabetes with no other complications. Earlier than that is considered where there are metabolic or other complications (recommendation 1.4.3).

For comparison, gestational diabetes in the same guideline is no later than 40 weeks plus 6 days. Two conditions, two windows. If a page quotes one figure for "diabetes in pregnancy" without saying which, it is not describing UK guidance accurately.

During labour, capillary plasma glucose is monitored hourly and kept between 4 and 7 mmol/litre. Diabetes is not a contraindication to vaginal birth after caesarean. If you also have a raised BMI or autonomic neuropathy, NG3 asks for a third-trimester anaesthetic assessment.

Afterwards

Insulin requirements fall steeply once the placenta is out, and your regimen is reviewed immediately. Your baby is monitored for low blood glucose and early feeding is encouraged. Longer term, your usual type 2 diabetes care resumes, and any medicines paused for pregnancy are reviewed against whether you are breastfeeding.

What other bodies say

ACOG's Practice Bulletin No. 201 on pregestational diabetes is the nearest US equivalent and is frank that "few well-designed studies have been performed" and that much of its guidance is expert and consensus opinion. Diabetes UK and HSE Ireland describe the same overall shape of care within their own systems. Where the numbers above differ from advice you have been given in another country, the difference is usually a genuine national policy choice rather than one of you being wrong.