Gestational diabetes mellitus

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Case history

A 28-year-old woman first presents for prenatal care at 24 weeks of gestation. Past medical history is notable for irregular periods and class I obesity (BMI 30 kg/m²). The results of a 75-gram oral glucose tolerance test performed after an overnight fast are: fasting glucose 105 mg/dL (5.8 mmol/L); 1-hour glucose 200 mg/dL (11.1 mmol/L); and 2-hour glucose 160 mg/dL (8.9 mmol/L).

Other presentations

Gestational diabetes mellitus (GDM) is usually diagnosed on the basis of an abnormal glucose tolerance test.[1] Less frequently, patients may present with symptoms of hyperglycemia, including polyuria or polydipsia. In the absence of glucose testing, the presence of macrosomia (birth weight >4000 g) raises suspicion that pregnancy may have been affected by unrecognized GDM. Occasionally it may be difficult to distinguish GDM from undiagnosed pre-existing type 2 diabetes. Infrequently, type 1 diabetes may also present during pregnancy.

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