Endocrine & metabolic · UKMLA & AKT
Gestational diabetes mellitus
A free high-yield preview for the UKMLA Applied Knowledge Test. Below are the key points to recognise gestational diabetes mellitus — the full SA Note notes add investigations, management, complications and 10 practice questions.
Key high-yield points
- GDM = carbohydrate intolerance first recognised or developing during pregnancy - distinct from pre-existing diabetes
- Gold standard: 75 g oral glucose tolerance test (OGTT) after ≥8 h overnight fast - fasting + 2-hour glucose
- NICE diagnostic thresholds (pregnancy-specific):
- Fasting glucose ≥5.6 mmol/L OR
- 2-hour glucose ≥7.8 mmol/L
- Either threshold alone is sufficient - a normal 2-hour result does not negate an elevated fasting glucose
- HbA1c is NOT used to screen for or diagnose GDM (altered red cell turnover in pregnancy makes it unreliable); useful in first trimester only to identify pre-existing undiagnosed diabetes
These thresholds differ from non-pregnant criteria (pre-diabetes, IGT, T2DM) - a common exam trap. In pregnancy, fasting ≥5.6 mmol/L = GDM regardless of the 2-hour result.
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