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.

Keywords: MODY (maturity‐onset diabetes of the young); diabetes mellitus; gestational diabetes mellitus; pregnancy; screening.