Gestational diabetes

Gestational diabetes means your blood sugar has become high during pregnancy. It often shows up on a blood test rather than through symptoms. It usually goes away after the birth, but follow-up tests still matter.

What changes during pregnancy

Insulin is a hormone that helps control blood sugar. During pregnancy, your body may not be able to make enough insulin to meet its extra needs. Gestational diabetes can happen even if you have none of the known risk factors.

Treatment lowers the risks to you and your baby. Possible problems include a baby who grows bigger than expected, difficulties during birth, and low blood sugar in the baby after birth. Your team will keep a close eye on you and offer treatment to lower those risks.

Who gets tested in the UK and US

In the UK, NICE recommends checking for risk factors at your booking appointment. These include having had gestational diabetes before, a close relative with diabetes, a higher body mass index (BMI), having had a large baby before, and being from an ethnic background where diabetes is more common. If you have these risk factors, you’ll be offered a test.

The test is an oral glucose tolerance test (OGTT). Blood samples are taken before and after a sugary drink to see how your body handles it. For most people tested because of risk factors, NICE gives a window of 24 to 28 weeks. If you’ve had gestational diabetes before, you’ll be offered an earlier test or early blood sugar checks, with another test later if needed.

In the US, ACOG recommends testing all pregnant women. Its patient guidance describes earlier tests for people with risk factors, and tests between 24 and 28 weeks for everyone else. Advice differs between countries. Ask which test you’re being offered and whether you need to prepare for it.

What a care plan can include

You’ll be shown how to check your blood sugar and share the results with your care team. Ask them to write down how to test, the targets they want you to aim for, and who to call about a reading. Use their plan when deciding what to do.

Advice on food and being active is part of treatment. NICE recommends seeing a dietitian. Talk about the meals you actually eat, your working day, the cost of food and any sickness that makes eating hard. Ask for a plan that fits your day.

You may also need medicine. NHS information describes metformin tablets or insulin injections. ACOG recommends insulin when medicine is needed, but accepts that tablets may sometimes be prescribed. Your doctor can explain the choice and show you how to use it. Follow the plan you agree with your prescriber.

Insulin can cause low blood sugar, also called a hypo. Ask your diabetes team how to spot and treat it. Signs include shaking, sweating, feeling hungry or finding it hard to concentrate. If you get these symptoms, follow your hypo plan straight away. Ask the team to explain when you need emergency help.

You may be offered extra appointments and scans. When you give birth, and whether induction or a caesarean is considered, depends on your blood sugar control, your health and the baby’s health. Ask your team to explain how these affect your birth plan.

Arrange the checks after birth

In the UK, NICE recommends a fasting blood sugar test 6 to 13 weeks after the birth. If diabetes is ruled out, it recommends a test every year after that. In the US, ACOG recommends a blood test 4 to 12 weeks after the birth. If diabetes is ruled out, it recommends testing every 1 to 3 years.

Having had gestational diabetes raises your risk of diabetes later in life, and of gestational diabetes in another pregnancy. Tell your GP or maternity clinician about it when you talk about a future pregnancy. Before you leave maternity care, ask who will book your test after the birth.

When to contact your team

Call 999 now (UK) or 911 (US), or your local emergency number, if someone who may have low blood sugar is unconscious or not responding normally, and there’s no glucagon or nobody knows how to use it. Don’t give food or drink to someone who is unconscious.

If you’re being treated for gestational diabetes and become unwell or get high blood sugar, contact your team now. In the UK, use your maternity or diabetes service. In the US, contact your obstetric clinician. Elsewhere, call your doctor or midwife. At your next appointment, ask for the number to call out of hours.

Book a GP or doctor appointment if, after the birth, you get more thirsty, need to pee more often or have a dry mouth. Don’t wait for your next planned diabetes test. A clinician needs to check these symptoms to find the cause.