Gestational DM - screening

• Screening for gestational diabetes is controversial. 

The cost-effectiveness of population screening is principally dependent on the prevalence of gestational diabetes and the acceptability of the screening test
• Testing for glycosuria has a poor sensitivity in detecting gestational diabetes 
- only ~40% of women with a 2h GTT >11mmol/l have glycosuria in the third trimester
• Random blood glucose has a poor sensitivity (~40%) in detecting gestational diabetes

• Measurement of fasting glucose on a population basis is difficult and has a low specificity

• Measurement of HbA1c also has low sensitivity
• The 50g oral glucose challenge test is the gold standard for screening