Gestational diabetes

Gestational diabetes means blood sugar has become high during pregnancy. It often turns up on a blood test rather than through symptoms. It usually goes away after 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 be unable to make enough to meet its extra needs. Gestational diabetes can happen even without recognised risk factors.

Treatment reduces the risks to you and your baby. Possible complications include a baby growing larger than expected, difficulties during birth and low blood sugar in the baby after birth. Your team will monitor you and offer treatment to reduce those risks.

Who gets tested in the UK and US

In the UK, NICE recommends checking risk factors at the booking appointment. These include previous gestational diabetes, a close family history of diabetes, higher body mass index, previously having a large baby, and ethnicity associated with a higher prevalence of diabetes. People with these risk factors are offered testing.

The test is an oral glucose tolerance test, or OGTT: blood samples are taken around a glucose drink to see how your body handles it. For most people being tested because of risk factors, NICE gives a window of 24 to 28 weeks. If you have had gestational diabetes before, you will be offered earlier testing or early glucose monitoring, with another test later if needed.

In the US, ACOG recommends screening all pregnant women. Its patient guidance describes earlier testing for people with risk factors and testing between 24 and 28 weeks otherwise. Advice differs between countries; ask which test you are being offered and whether you need to prepare for it.

What a care plan can include

You will be shown how to check your blood sugar and share the results with your care team. Ask them to write down your testing instructions, the targets they want you to use and who to call about a reading. Use their plan when deciding what action to take.

Food advice and physical activity are part of treatment. NICE recommends referral to a dietitian. Talk about meals you actually eat, your working day, food costs and any sickness that makes eating difficult. Ask for a plan that fits your day.

Medicine may also be needed. NHS treatment information describes metformin tablets or insulin injections; ACOG recommends insulin when medicine is needed, while acknowledging that oral medicine may sometimes be prescribed. Your doctor can explain the choice and teach you how to use it. Follow the plan agreed with your prescriber.

Insulin can cause low blood sugar, also called a hypo. Ask your diabetes team how to recognise and treat it, including symptoms such as shaking, sweating, hunger or difficulty concentrating. Follow your agreed hypo plan promptly if symptoms occur, and ask the team to explain when emergency help is needed.

Extra appointments and scans may be offered. When you give birth, and whether induction or caesarean birth is considered, depend on glucose 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 glucose test 6 to 13 weeks after birth and annual testing afterwards if diabetes is excluded. In the US, ACOG recommends a blood test 4 to 12 weeks after birth, then testing every 1 to 3 years if diabetes is excluded.

Having had gestational diabetes raises the risk of diabetes later and of gestational diabetes in another pregnancy. Tell your GP or maternity clinician about it when discussing a future pregnancy. Ask who will book your post-birth test before you leave maternity care.

When to contact your team

Call 999 now (UK) or 911 (US), or your local emergency number, if someone with suspected low blood sugar is unconscious or not responding appropriately and no glucagon is available or nobody knows how to use it. Do not give food or drink to someone who is unconscious.

Contact your maternity or diabetes team now if you become unwell or develop high blood sugar while being treated for gestational diabetes. In the UK, use your maternity or diabetes service; in the US, contact your obstetric clinician; elsewhere, call your doctor or midwife. Ask for the out-of-hours contact at your next appointment.

Book a GP or doctor appointment if you develop increased thirst, more frequent urination or a dry mouth after birth. Do not wait for the next scheduled diabetes test. A clinician needs to assess these symptoms to find the cause.