Management of GCK-MODY in Pregnancy—Does Clinical Practice Follow Current Recommendations?

Recommendations for management of GCK-MODY during pregnancy are based on fetal genotype. Women with GCK-MODY should not be treated with insulin prior to conception and insulin should not be given if normal fetal growth is observed. Women should be treated with insulin if fetal ultrasound monitoring starting at 26 weeks shows macrosomia, suggesting the fetus is wild type for the GCK gene. There is limited data about management of GCK-MODY in pregnancy. The aim of this study was to examine clinical management and pregnancy outcomes amongst women with a known diagnosis of GCK-MODY. A survey was distributed via Redcap to 94 women >/= 18 years enrolled in the University of Chicago Monogenic Diabetes Registry. All or part of the survey was completed by 59% of women. GCK-MODY diagnosis was known at the time of pregnancy for 14 women with a total of 18 pregnancies, including 2 women who were currently pregnant. There were 13 term births and 3 premature births. Glucose-lowering therapy was used preconceptually in 33% of cases, including insulin use in 3 women. Insulin was started in 7 pregnancies; in 4 cases the fetus measured normal for dates and in 3 cases measured large. Insulin was started between 5-32 weeks (average 16.4 weeks). Insulin treatment was not started in 1 pregnancy where the baby measured large for dates and early induction was required. This offspring was WT for GCK. In our study, contrary to current recommendations, one-third of pregnancies were treated with glucose-lowering medication prior to pregnancy, including insulin. Insulin initiation occurred early in gestation (average 16.4 weeks), rather than being based on fetal size on ultrasound monitoring. These observations suggest that for many pregnancies affected by GCK-MODY, management does not reflect current guidelines. Further studies to confirm the safety and efficacy of the current recommendations may improve provider confidence in deferring insulin treatment in cases where ultrasound monitoring shows normal fetal growth.