Most women's blood sugar levels remain normal during pregnancy. But if blood sugar levels go above a certain value, they are considered to have gestational diabetes. This is the case in about 4 out of 100 women.
It is not always clear whether a woman just has slightly higher blood sugar levels or whether she has gestational diabetes. Women’s metabolism changes over the course of pregnancy anyway: It takes longer for the cells in their body to absorb the sugar in their blood after meals. This means that elevated blood sugar levels are often a normal part of pregnancy – and they usually return to normal afterwards. Having gestational diabetes doesn’t mean that you have developed chronic diabetes.
The raised blood sugar levels in gestational diabetes slightly increase the risk of certain rare birth complications. This risk can usually be lowered by changing your diet, though.
The vast majority of women who develop gestational diabetes experience an otherwise normal pregnancy and go on to give birth to a healthy baby.
High blood sugar levels are more common in women who
- are heavily overweight,
- have had gestational diabetes in the past, or
- have close relatives with diabetes.
Your doctor might already ask you about these factors early in your pregnancy and then advise you to be tested for gestational diabetes.
Gestational diabetes usually doesn’t have any consequences for the mother and child. Babies born to women who have gestational diabetes have a slightly heavier birth weight on average. But this is not a reason for concern.
During the birth of larger babies, the phase after the head has come out often takes longer. If the child's shoulder gets stuck in the mother's pelvis (a situation known as “shoulder dystocia”), the child may not get enough oxygen. Midwives and doctors then react quickly to be on the safe side. This can lead to small injuries in the child and sometimes in the mother. Although these usually heal well, being in that situation can be distressing for the mother. Shoulder dystocia occurs in about 4 out of 100 children whose mothers had gestational diabetes and didn’t have it treated. But emergency situations and more severe injuries are rare.
Higher blood sugar levels also increase the risk of a rare problem during pregnancy known as pre-eclampsia. This condition is associated with excess protein in the urine, which causes high blood pressure and water retention in the body. Left untreated, pre-eclampsia can harm both the mother and the child.
Women with gestational diabetes are somewhat more likely to develop type 2 diabetes later in life.
The best way to diagnose gestational diabetes is by doing a glucose tolerance test. The test measures how the body reacts to a large amount of glucose (sugar). It is offered in the sixth or seventh month of pregnancy and involves a shorter initial test (a glucose challenge test) followed by the normal glucose tolerance test.
For the shorter test, you drink a glass of water with sugar dissolved in it. One hour later, a sample of blood is taken from a vein in your arm to determine the blood sugar level. If the level is found to be high, the second test is done. This is done in a similar way but involves a bit more time and effort. For instance, it has to be done on an empty stomach.
The results are documented in your maternity records. In Germany, the costs of glucose tolerance tests are covered by statutory health insurers.
Pregnant women who get enough exercise and eat a balanced diet are less likely to develop gestational diabetes than women who are overweight or eat a lot of carbohydrates. But it’s not unusual for pregnant women to have higher blood sugar levels – simply because their metabolism is different.
A change in diet is usually enough to make the levels return to normal. Women with gestational diabetes can get advice from their doctor. Special dietary counseling can be helpful too. Another way to lower your blood sugar levels is by getting more exercise. In some pregnant women the blood sugar levels stay high for so long that they have to inject insulin or, in rare cases, take medicine for diabetes.
The doctor will offer to measure the woman’s blood sugar levels again after the baby is born. If her blood sugar levels have returned to normal, no more treatment is needed.
Because gestational diabetes usually doesn’t cause any symptoms, women are often surprised to find out they have it. Many then start to worry about whether their baby is okay or whether the diabetes will cause problems during birth. Some may be afraid that they’ll still have diabetes after their baby is born. These kinds of concerns can be distressing during pregnancy. So it is important to be aware that the vast majority of women with gestational diabetes give birth to healthy children.
The necessary changes in diet and physical activity may take some getting used to at first. But they can soon become a normal part of your daily life and help you keep fit after pregnancy too.
Gemeinsamer Bundesausschuss (G‑BA). Richtlinien über die ärztliche Betreuung während der Schwangerschaft und nach der Entbindung.
Institut für angewandte Qualitätsförderung und Forschung im Gesundheitswesen (AQUA). Bundesauswertung zum Erfassungsjahr 2014. 16/1 - Geburtshilfe. June 23, 2015.
Institute for Quality and Efficiency in Health Care (IQWiG, Germany). Screening for gestational diabetes: Final report; commission S07-01; Version 1.1. August 25, 2009. (IQWiG reports; Volume 58).
Rayanagoudar G, Hashi AA, Zamora J, Khan KS, Hitman GA, Thangaratinam S. Quantification of the type 2 diabetes risk in women with gestational diabetes: a systematic review and meta-analysis of 95,750 women. Diabetologia 2016; 59(7): 1403-1411.
Rogozinska E, Chamillard M, Hitman GA, Khan KS, Thangaratinam S. Nutritional manipulation for the primary prevention of gestational diabetes mellitus: a meta-analysis of randomised studies. PLoS ONE 2015; 10(2): e0115526.
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