Gestational diabetes mellitus

Gestational diabetes mellitus (GDM) develops during pregnancy and is usually diagnosed at 24 to 28 weeks of gestation on the basis of elevated plasma glucose levels on glucose tolerance testing.

Goal of therapy is to achieve maternal glucose levels that are as close to normal as possible in order to avoid fetal macrosomia and complications.

Initial therapy for GDM is usually dietary modification. Insulin is started when acceptable glucose levels cannot be maintained with diet alone.

Maternal postpartum testing for diabetes or impaired glucose tolerance is performed at 4 to 6 weeks following delivery.

The risk for recurrence of GDM in subsequent pregnancies or progression to type 2 diabetes is high.

GDM was previously defined as any degree of glucose intolerance with onset or first recognition during pregnancy. This definition included a population of women with preexisting type 2 diabetes, so the definition has been modified to indicate that the diagnosis is after the first trimester of pregnancy.[1]American Diabetes Association. Standards of care in diabetes - 2025. Diabetes Care. 2025 Jan 1;48(suppl 1):S1-352. https://diabetesjournals.org/care/issue/48/Supplement_1 It is usually recognized at 24-28 weeks of gestation on the basis of abnormal glucose tolerance testing.[1]American Diabetes Association. Standards of care in diabetes - 2025. Diabetes Care. 2025 Jan 1;48(suppl 1):S1-352. https://diabetesjournals.org/care/issue/48/Supplement_1 ​ The criteria for diagnosing GDM remain controversial.​