Home / Glossary / Gestational diabetes
Conditions

Gestational diabetes

Diabetes first detected during pregnancy

Gestational diabetes — glucose control in pregnancy

Gestational diabetes (GDM) is a disorder of carbohydrate metabolism first detected during pregnancy. The hormones of the placenta increase insulin resistance; if the pancreas cannot keep up with compensation, blood sugar rises.

GDM is usually asymptomatic and detected only by a glucose tolerance test, which is why it is deliberately screened for.

Why it is dangerous

High maternal blood sugar leads to excessive fetal growth (a large baby), delivery complications and hypoglycemia in the newborn. For the woman herself, GDM is a marker of an increased risk of type 2 diabetes in the future.

How it is detected

An oral glucose tolerance test with 75 g of glucose, usually at 24–28 weeks (earlier if there are risk factors). The diagnosis is made if at least one of the three values reaches the threshold.

After delivery

Most often GDM resolves after delivery. But the risk of type 2 diabetes remains elevated — control of glucose and HbA1c and a healthy lifestyle are recommended.

Reference ranges

WHO (2013) / IADPSG criteria — a test with 75 g of glucose, one value is enough:

Fasting≥ 5.1 mmol/L
At 1 hour≥ 10.0 mmol/L
At 2 hours≥ 8.5 mmol/L
Important: The thresholds for pregnant women are lower than the usual “diabetic” ones — because even moderately elevated blood sugar affects the fetus (data from the HAPO study).

Calculate using this marker

Calculators where Gestational diabetes is used directly:

Diabetes Risk Screening for hidden prediabetes and type 2 diabetes from labs and risk factors Open

Frequently asked questions

Will gestational diabetes go away after delivery?

Usually yes — after the placenta is delivered the hormonal load is removed, and blood sugar normalizes. But it is important for the woman to be tested at 6–12 weeks and then regularly: the risk of type 2 diabetes later on is increased.

Is GDM dangerous for the baby?

With good blood sugar control the risks are minimal. Without control, a large fetus, birth injuries and a drop in the newborn's blood sugar are possible, so GDM is actively managed with diet, self-monitoring and, if necessary, insulin.

Related terms

Type 2 diabetes mellitus Persistently high sugar due to insulin resistance and a relative lack of insulin Insulin resistance Reduced sensitivity of cells to insulin Fasting glucose Fasting blood sugar — the main marker of carbohydrate metabolism Prediabetes Sugar above normal but not yet diabetes — a reversible "yellow zone" Diabetes mellitus A chronic disorder of glucose metabolism: type 2 is linked to insulin resistance and sharply raises cardiovascular risk.

Sources

  1. WHO. Diagnostic criteria and classification of hyperglycaemia first detected in pregnancy, 2013
  2. IADPSG. Recommendations on diagnosis and classification of hyperglycemia in pregnancy. Diabetes Care, 2010
  3. MedlinePlus (NIH) — Diabetes and Pregnancy
info
This content is educational and does not replace consultation with a physician. Reference ranges may vary depending on the laboratory and method — rely on the ranges stated on your own test report.
← All glossary terms