Gestational diabetes is one of the most common complications of pregnancy. The number of pregnant women affected in all age groups has risen steadily in recent years. Among other things, this development is associated with the increasing average BMI (body mass index) of expectant mothers.
Furthermore, gestational diabetes occurs more frequently as pregnant women get older. A test for gestational diabetes in the 24th to 28th week of pregnancy has therefore been part of maternity care in Germany since 2012. An evaluation of these screenings from 2014 and 2015 revealed an average incidence of gestational diabetes of 13.2 percent in Germany. In women aged 45 or older, the sugar metabolism disorder even occurs in 26% of all pregnancies.
The hormone insulin is released by the pancreas when blood glucose levels are high and causes glucose to be absorbed by the body's cells. The hormones that are increasingly produced during pregnancy, in particular cortisol and progesterone, are insulin antagonists, i.e. they reduce the effectiveness of insulin. This is referred to as insulin resistance. A certain tendency towards insulin resistance develops in most pregnancies in the second trimester. This is not yet a disease in itself, but presumably serves to prioritize the supply of glucose to the foetus.
However, if the insulin resistance can no longer be compensated for by increased insulin secretion, gestational diabetes develops. This can be the case, for example, if subliminal, typically diet-related disorders of glucose metabolism were already present before pregnancy, insulin secretion was already increased and the pancreas was already working close to its capacity limit.
The greatest risk factors for gestational diabetes are obesity, advanced age and the metabolic disorder polycystic ovary syndrome(PCOS). However, the limitation of possible insulin production can also have genetic causes that are not related to these risk factors.
Gestational diabetes leads to reduced glucose tolerance, i.e. an increased blood sugar level after ingesting carbohydrates. This does not usually cause any noticeable symptoms for those affected.
An increased feeling of thirst, accelerated weight gain and increased blood pressure can be indications of the metabolic disorder. Furthermore, sugar in the urine and associated urinary tract and kidney infections occur more frequently. The foetus may exhibit growth disorders that become apparent during ultrasound diagnostics.
Gestational diabetes is diagnosed with the so-called oral glucose tolerance test (oGTT). This involves drinking 75 grams of glucose dissolved in 300 milliliters of water within five minutes on an empty stomach in the morning. Blood samples are then taken at different times (before the glucose intake and one and two hours afterwards) to measure the time course of the resulting blood sugar increase.
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Blood glucose levels above a threshold value can be used to detect the presence of gestational diabetes. According to a recommendation by the International Association of the Diabetes and Pregnancy Study Groups (IADPSG), the current threshold values are 92, 180 and 153 mg/dl before glucose intake and one hour and two hours after. Incidentally, screening for gestational diabetes is one of the prenatal care services financed by health insurance.
If there are no risk factors, the short version of the oGTT is used here. You drink 50 grams of glucose in 200 milliliters of water at the doctor's and after an hour your blood is drawn. If the screening shows an abnormal blood glucose value, an examination with the glucose tolerance test described above will be arranged.
Most women can normalize their blood sugar levels by changing their diet (largely replacing simple carbohydrates such as sugar and white flour with complex carbohydrates such as wholemeal flour and eating more frequent, small meals) and taking more exercise. In around one in ten women, insulin therapy is also necessary. This involves injections with an insulin pen, often in combination with close blood glucose monitoring.
Treatment with the oral diabetes drug metformin alone or in addition is also being discussed. However, the safety and efficacy of this treatment have not yet been sufficiently proven. Metformin is therefore not approved for pregnant women in Germany and can only be prescribed in exceptional cases.
If gestational diabetes is detected in time and it is possible to control the blood sugar level through lifestyle changes or insulin therapy, the prognosis for mother and child is good: most of the women affected experience a completely normal pregnancy and delivery. Nevertheless, there is still a slight increase in the complication rate. Gestational diabetes therefore increases the risk of:
After delivery, the blood sugar metabolism largely normalizes and gestational diabetes usually
disappears again. However, the
risk of developing
type 2 diabetes in the near future remains significantly (up to seven times)
higher: after all, gestational diabetes is an indication of a pre-existing underlying disorder of blood glucose metabolism. For this reason, affected women should also have their
blood sugar levels checked regularly after giving birth.
