Shortcut to the needle in the haystack? Screening for maturity onset diabetes of the young in a population of women with gestational diabetes

Abstract

Aims

Pregnant women are occasionally misdiagnosed with gestational diabetes (GDM) when they may have glucokinase monogenic diabetes (GCK-MODY). Differentiating between GCK-MODY and GDM is critical due to the distinct treatment strategies required during and after pregnancy. Since pregnancy often elicits the first glucose tolerance test, it provides a unique opportunity to identify individuals with GCK-MODY. However, testing all pregnant women with GDM for GCK-MODY is expensive, and the use of clinical criteria is warranted. An Irish study suggested using a combined criteria of a pre-pregnancy body mass index (BMI) <25 kg/m² and fasting glucose ≥5.5 mmol/L to differentiate GCK-MODY from GDM. Therefore, we aimed to identify women with GCK-MODY during pregnancy using these combined criteria in a Danish population of women with GDM. Additionally, we aimed to screen for other MODY subtypes.

Methods

We recruited women from the Central Denmark Region diagnosed with GDM between April 2019 and December 2022. Women meeting the criteria of pre-pregnancy BMI <25 kg/m² and fasting glucose ≥5.5 mmol/L were offered screening for MODY (17 known genetic variants) using Illumina's Next Generation Sequencing.

Results

Of the 1270 women with GDM, 46 met the MODY screening criteria. Of these, 41 were offered MODY screening, 34 participated and 1 woman was identified with MODY (MODY 8–CEL variant).

Conclusion

The current Danish GDM screening guidelines do not apply with recommending the use of pre-pregnancy BMI <25 kg/m² and fasting glucose ≥5.5 mmol/L as criteria for identifying women with GCK-MODY among women with GDM in the Danish population.