Gestational diabetes mellitus (GDM) – colloquially known as gestational diabetes – (ICD-10-GM O24.4: Diabetes mellitus, occurring during pregnancy) is a glucose tolerance disorder or diabetes mellitus (diabetes) occurring for the first time during pregnancy (gestation). In rare cases, it is new-onset diabetes mellitus type 1 or type 2.
A fasting glucose (fasting blood sugar) between 92-125 mg/dl (5.1-6.9 mmol/l) is classified as gestational diabetes. The transitions between so-called normal glucose tolerance in pregnancy and gestational diabetes are fluid; a threshold value does not exist. The determination of an occasional blood glucose should not be used as a screening method for GDM because of its low sensitivity (strength of recommendation B). The gold standard is the 50-g glucose screening test (glucose challenge test, GCT). A fasting glucose of ≥ 126 mg/dl (> 7.0 mmol/l) is classified as manifest diabetes mellitus.
Peak incidence: gestational diabetes usually manifests in the 2nd or 3rd trimester (third trimester) of gravidity (pregnancy).
The prevalence (disease incidence) is approximately 1-20% worldwide – with an increasing trend.The 1-year prevalence in Germany shows an increase with age from 8% to 26% (≥ 45 years); the overall prevalence is 13.2%.
Course and prognosis: In typical gestational diabetes, glucose metabolism returns to normal in most women after birth. The risk of developing diabetes mellitus later remains elevated. 35-60% of women with gestational diabetes develop glucose tolerance disorders within 10 years. In addition, women with gestational diabetes have an increased risk (35-50%) of recurrent diabetes in subsequent pregnancies.
