Gestational diabetes: screening, diagnosis and management
Gestational diabetes is a form of high blood sugar that can develop during pregnancy, even in people who have never had diabetes before. The body normally increases its insulin output to handle the hormonal changes of pregnancy, but sometimes the pancreas cannot keep up with that extra demand. The result is blood glucose levels that rise higher than normal. Because the condition almost never causes noticeable symptoms, it is picked up through a screening test rather than through anything you would feel, which is why knowing whether you are in a higher-risk group matters.
Who is at higher risk
The NHS identifies several factors that increase the likelihood of developing gestational diabetes. A body mass index above 30 before pregnancy is one of the most common risk factors. Having had gestational diabetes in a previous pregnancy also significantly raises the chance of it recurring. A family history of type 2 diabetes in a close relative, or having previously given birth to a baby weighing more than 4.5 kg, are also recognised risk factors. Certain ethnic backgrounds carry a higher risk too: people of South Asian, Black, Middle Eastern or Caribbean heritage are more likely to develop the condition. Age is a further consideration, with people aged 35 and over at greater risk than younger pregnant people.
If one or more of these factors applies to you, your midwife should discuss the GTT with you at an early appointment. The presence of risk factors does not mean you will develop gestational diabetes, only that screening is recommended.
How screening works: the glucose tolerance test
The standard screening tool used by the NHS is the oral glucose tolerance test, often called the GTT or OGTT. It is typically offered between 24 and 28 weeks of pregnancy to people identified as higher risk. The process involves fasting from the evening before the test, attending a clinic for a blood sample, drinking a measured glucose solution, and then waiting two hours before a second blood sample is taken. The two readings together tell the team how well your body is processing sugar. Results are usually available within a few days, and your midwife or diabetes team will contact you to discuss them if any follow-up is needed.
Managing gestational diabetes
A diagnosis of gestational diabetes does not automatically mean you will need medication. The first step in management is monitoring your blood glucose at home using a small testing kit, so your care team can see how your levels change across the day and in response to meals. Alongside this, most people are advised to make changes to the way they eat, focusing on reducing foods that cause rapid rises in blood sugar, such as white bread, sugary drinks and processed snacks, and replacing them with slower-releasing carbohydrates, fibre and regular balanced meals. Staying physically active is also an important part of management, as gentle movement helps the body use insulin more efficiently.
If dietary changes and physical activity are not enough to bring blood sugar within the recommended range, your team may recommend medication. Metformin tablets are often the first option considered. If metformin is not suitable or does not achieve the target levels, insulin injections are used instead. Your care team will guide you through how to use insulin safely and what to expect. Some people require insulin from early in their diagnosis; others manage entirely without medication throughout the pregnancy.
Risks of poorly managed gestational diabetes
When blood glucose levels stay elevated throughout pregnancy without adequate management, there are potential complications for both the pregnant person and the baby. One of the most common is the baby growing larger than expected, a condition called macrosomia. A larger baby can make labour more difficult and increases the risk of shoulder dystocia, where the baby's shoulders become briefly lodged during delivery. There is also a higher risk of premature birth, pre-eclampsia and a higher rate of caesarean birth in pregnancies affected by gestational diabetes. These risks are not inevitable, and effective management significantly reduces them, which is why close monitoring throughout the pregnancy is important.
After the birth: your long-term health
For most people, blood sugar levels return to normal within a short time of delivering the baby, and gestational diabetes resolves on its own. However, the NHS recommends a blood test between 6 and 13 weeks after birth to confirm that glucose levels have normalised. This is an important check because, in a small number of cases, blood sugar remains elevated after delivery, indicating that diabetes was already present before pregnancy. Beyond that initial check, the NHS recommends an annual HbA1c blood test going forward, because having had gestational diabetes is a significant risk factor for developing type 2 diabetes later in life. Staying active, maintaining a healthy weight and eating well all help reduce that longer-term risk. Your baby also has a slightly elevated risk of developing type 2 diabetes in adulthood, something worth being aware of as they grow up.
Frequently asked questions
What is gestational diabetes?
Gestational diabetes is high blood sugar that develops during pregnancy in someone who did not have diabetes before. It happens because pregnancy hormones make the body less sensitive to insulin, and the pancreas cannot always produce enough extra insulin to compensate. It usually resolves after the baby is born.
How is gestational diabetes diagnosed?
The NHS uses a glucose tolerance test (GTT). You fast overnight, have a blood test, drink a glucose solution, and have another blood test two hours later. The test is offered to people with risk factors, usually between 24 and 28 weeks.
Can gestational diabetes be managed without medication?
Many people manage gestational diabetes successfully through dietary changes and regular physical activity. This means reducing foods that cause rapid blood sugar rises, eating regular balanced meals and checking blood glucose levels at home. If blood sugar remains high despite these measures, your team may recommend metformin tablets or insulin injections.
Does gestational diabetes go away after birth?
In most cases, yes. Blood sugar levels usually return to normal shortly after delivery. However, the NHS recommends a blood test 6 to 13 weeks after birth to confirm this, and ongoing annual checks thereafter, as gestational diabetes is a risk factor for developing type 2 diabetes later in life.
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