Gestational diabetes: causes, symptoms and treatment

Gestational diabetes (also known as gestational diabetes mellitus) refers to elevated blood sugar levels that are first detected during pregnancy. It often only becomes apparent later on, which is why a test is generally recommended between the 24th and 28th weeks of pregnancy. People with no known history of diabetes before pregnancy can also be affected.

In Switzerland, gestational diabetes occurs in about 10–15% of all pregnancies. This makes it one of the most common pregnancy complications. Gestational diabetes can generally be kept under control with the right treatment. What’s more, many people find their blood sugar levels return to normal once they’ve given birth. Early diagnosis and making a few lifestyle changes can help to significantly reduce potential risks for both the pregnant person and their child.

A person’s metabolism changes during pregnancy. Certain pregnancy hormones can cause the body’s cells to become less sensitive to insulin, a hormone produced by the pancreas that helps carry sugar from the blood into the cells. This means that the body’s need for insulin increases during pregnancy. 

Normally, the pancreas compensates for this increased demand by producing more insulin. However, if it’s unable to produce enough, too much sugar remains in the blood. This leads to gestational diabetes. 

• Being overweight
• A lack of exercise or an unbalanced diet
• Diabetes mellitus in the family
• Gestational diabetes in previous pregnancies
• Being over 30 years of age
• A history of multiple miscarriages
• Certain types of medication, such as cortisone preparations
• Illnesses that are associated with insulin resistance (e.g. PCOS)

When it comes to gestational diabetes, the typical signs of diabetes often occur in a mild form, if at all. As a result, many of those affected don’t even realise they have the condition. In most cases, gestational diabetes is only detected by the recommended blood glucose test carried out during pregnancy.

Where blood sugar is significantly elevated, non-specific complaints may occur, such as:

• Being unusually thirsty
• Urinating more frequently
• Dry mouth
• Tiredness or weakness
• Blurred vision
• Genital itching or fungal infections

Remember that gestational diabetes doesn’t usually cause any clear symptoms. There are generally no directly observable signs in the unborn child either. If diabetes in pregnancy goes unnoticed or untreated, however, it can increase the risk to the pregnant person and their baby. This is why screening is especially important during pregnancy.

If left untreated or not properly managed, gestational diabetes can have various effects on the pregnant person and their child. That’s why early diagnosis and keeping blood sugar levels under control are particularly important. Possible complications for the pregnant person include:

• Preeclampsia: gestational diabetes can increase the risk of preeclampsia. This is usually accompanied by high blood pressure and other signs that the organs are affected, such as protein in the urine, liver or kidney dysfunction, severe headaches, impaired vision or pain in the upper abdomen. Preeclampsia was also known as “toxaemia” in the past, but this term is now considered outdated.
• Eclampsia: in rare severe cases, preeclampsia may develop into eclampsia. This can lead to seizures, which can be dangerous for both the pregnant person and the unborn child. Warning signs such as severe headaches, impaired vision or neurological complaints should therefore always be investigated by a doctor as soon as possible.
• HELLP syndrome: HELLP syndrome is a rare but serious complication of pregnancy associated with changes in liver function tests and blood platelet counts, among other things. Possible warning signs include severe pain in the right upper abdomen, nausea, vomiting or a pronounced feeling of being unwell. If you develop symptoms like these, it’s important to see a doctor as quickly as possible.
• Premature birth: gestational diabetes can increase the risk of premature birth. An excess of amniotic fluid, infections and other pregnancy complications can all contribute to this. However, early diagnosis and keeping blood sugar levels under control can significantly reduce many of the risks.
• Birth complications: in cases of gestational diabetes, babies are often bigger or heavier. This can make labour more difficult and increase the risk of birth injuries. It may also become necessary to induce labour or carry out a caesarean section. Whether a vaginal birth is possible or a caesarean section is recommended depends on the individual situation; a decision will be made in consultation with the treatment team.

In addition, gestational diabetes can also have a number of effects on the child:

• Macrosomia: if the pregnant person has high blood sugar levels, the unborn child will also receive more glucose. In response, the child will produce more insulin. This can lead to an above-average growth rate and a higher birth weight. Cases where the birth weight is more than 4000 grams are often referred to as macrosomia. Larger babies are more likely to suffer from birth complications. Children can also experience adaptation issues after the birth, such as hypoglycaemia, breathing problems or jaundice.
• Malformations: there is a particularly high risk of malformations if blood sugar levels are significantly elevated in the first weeks of pregnancy, for example in the case of diabetes that existed before the pregnancy or had not yet been diagnosed. Typical gestational diabetes usually only develops later during pregnancy. That’s why it’s important to consider this connection on a case-by-case basis.

Gestational diabetes: long-term impacts for mother and child

Around 40% of women who have had gestational diabetes in a previous pregnancy develop gestational diabetes again in subsequent pregnancies. In addition, 25% to 50% of women who have suffered from gestational diabetes develop type 2 diabetes within 5 to 10 years. The children of these women also have an increased risk of becoming overweight and developing high blood pressure and diabetes, all of which are risk factors for cardiovascular disease.

Between the 24th and 28th week of pregnancy, doctors carry out a major gestational diabetes test. The first step is to determine the mother’s fasting blood sugar level. The oral glucose tolerance test during pregnancy involves drinking a glucose solution on an empty stomach within a few minutes. After an hour, the doctor takes a blood sample and measures her blood sugar levels again. If these are elevated, another test follows. The healthcare professional will check her blood sugar levels after another hour has passed, which is two hours after determining the fasting level.

What are the blood glucose levels of those affected by gestational diabetes? With gestational diabetes, at least one of the following levels is elevated:

• Cut-off level for fasting blood sugar: 5.1 mmol/L
• Cut-off level for blood sugar after one hour: 10 mmol/L
• Cut-off value for blood sugar after two hours: 8.5 mmol/L

Please note: you should not eat anything after 10 pm the day before having an oral blood glucose test during pregnancy. Also avoid drinking sweetened drinks and fruit juices, but opt for still water instead. Do not do any exercise either. All of this influences blood glucose levels and may make it difficult to correctly diagnose gestational diabetes.

Both mild and severe gestational diabetes must be treated. Sometimes all that is required is a change of diet. Some people, however, will need to take insulin. If your gynaecologist has diagnosed you with gestational diabetes, they will refer you to a diabetologist. You will discuss the next steps for managing gestational diabetes with this specialist. Women with gestational diabetes generally learn how to measure their blood sugar levels themselves. In the first one to two weeks after their diagnosis, they measure it four times a day: the fasting level in the morning and then one to two hours after each main meal. After this, one measurement per day is often sufficient.

Gestational diabetes: what can you eat? 

The primary focus during pregnancy is your nutrition. You should eat less fat and more protein. Generally, you should reduce your carbohydrate intake, and eat higher-value carbohydrates. Gestational diabetes is usually easy to manage with a balanced diet. 

But what does an optimal diet look like when it comes to gestational diabetes? Experts recommend the following daily macro split for those affected:

• 40% to 50% carbohydrates: opt for wholegrain products if you can. Foods made from white flour cause blood sugar levels to rise sharply.
• 30% to 35% fats: if you have gestational diabetes, eat foods that contain vegetable fats and oils.
• 20% protein: choose low-fat milk or dairy products, for example. It’s also a good idea to eat low-fat meat such as poultry.
• At least 30 grams of fibre: this is found in wholegrain products and pulses, among other things. 

A nutrition plan is particularly important for those who have gestational diabetes. This makes it easier when adjusting their diet. Below is an example of such a plan:

It’s better to eat several small meals rather than a few larger ones in order to avoid spikes in your blood sugar levels. You should also cut down on soft drinks and sugary foods; zero-sugar and diet drinks are okay from time to time. Always follow the recommendations of your diabetologist. Dietary changes, such as the Louwen diet, that are not designed for gestational diabetes are best discussed with a medical professional in advance.

Remember that it’s best to avoid having dried fruits as a snack, as they contain concentrated fructose and can cause blood sugar levels to rise more quickly. Smaller portions of fresh fruit with some protein or a few nuts are more suitable.

Exercising with gestational diabetes

Also make sure to get enough exercise on a daily basis. What do you need to consider in this respect if you have gestational diabetes? Engage in 30 minutes of moderate exercise at least three times a week. Gentle movement during pregnancy, such as swimming or specific courses for expectant mothers, is a great option. Getting enough exercise is important because it may help your cells to absorb insulin better and break down glucose more effectively.

Gestational diabetes: at what point do you need to start taking insulin?

People with gestational diabetes regularly measure their blood sugar levels themselves. They then review the results with their doctor or a diabetes specialist. Blood glucose levels can often be sufficiently reduced with a modified diet and regular, pregnancy-appropriate exercise.

If the values repeatedly remain above the target range despite these changes, insulin-based treatment may be necessary.

After the birth: gestational diabetes check-up

In most cases, gestational diabetes disappears on its own shortly after birth. To be on the safe side, however, your doctor will carry out another blood sugar test around six weeks after your baby is born. After that, a yearly check is sufficient. The risk of developing type 2 diabetes is still higher for years after having gestational diabetes.

After the birth, a specialist will check your child’s blood sugar levels regularly. Proper nutrition is very important for your child’s metabolism to adapt. Your midwife, nursing staff and lactation consultants will be happy to advise you on this topic.

By the way, pregnant women with diabetes can express their first milk (colostrum) shortly before giving birth and then freeze it. Give this to your child after birth if necessary.

It is not yet clear whether and how gestational diabetes can be prevented. However, experts recommend that women who are overweight lose weight. This helps them to reduce their risk of developing gestational diabetes. Weight loss can be achieved, for example, by changing your diet and moving more.

Gestational diabetes is no reason to panic. A pregnancy with well-managed gestational diabetes usually proceeds without any problems. Take all medical check­ups seriously and consult your doctor if you are unsure about anything.