The impact of new national guidelines on screening for gestational diabetes mellitus.

Gestational diabetes mellitus (GDM) has important maternal and fetal implications. In 2010, the Health Service Executive published guidelines on GDM. We examined the impact of the new guidelines in a large maternity unit. In January 2011, the hospital replaced the 100 g Oral Glucose Tolerance Test (OGTT) with the new 75 g OGTT. We compared the first 6 months of 2011 with the first 6 months of 2010. The new guidelines were associated with a 22% increase in women screened from 1375 in 2010 to 1679 in 2011 (p < 0.001). Of the women screened, the number diagnosed with GDM increased from 10.1% (n=139) to 13.2% (n=221) (p<0.001).The combination of increased screening and a more sensitive OGTT resulted in the number of women diagnosed with GDM increasing 59% from 139 to 221 (p = 0.02).This large increase has important resource implications but, if clinical outcomes are improved, there should be a decrease in long-term costs.