Glucose tolerance two years after gestational diabetes classified by old Swedish or new WHO diagnostic criteria

Aim

To explore how introduction of the lower WHO gestational diabetes (GDM) glucose criteria in Sweden affected prediabetes/type-2-diabetes (T2D) incidence two years postpartum.

Methods

Women included in the PREvention of PostPartum (PREPP) diabetes study were diagnosed with GDM according to EASD 1991 criteria (GDM_OLD; n = 93) or only WHO 2013 criteria (GDM_WHO; n = 174). Both groups were further stratified by BMI, and BMI-matched normoglycemic pregnancy controls were included (n = 88). Postpartum assessments included oral glucose tolerance tests (OGTT) and anthropometric measurements.

Results

There was a higher postpartum incidence of T2D in GDM_OLD versus GDM_WHO (P < 0.001). Despite similar BMI, GDM_OLD exhibited higher fasting and OGTT glucose levels, lower fat-free-mass, and hip circumference compared to GDM_WHO. In normal-weight women, both GDM groups displayed higher HOMA-IR and lower fat-free-mass compared to controls, with GDM_OLD additionally showing lower HOMA-β, slower insulin release during OGTT, and worse glucose tolerance than GDM_WHO. Among obese women, the main differences were lower fat-free-mass and hip circumference in GDM_OLD.

Conclusion

The lower glucose cut-offs during pregnancy resulted in lower postpartum incidence of T2D, irrespective of BMI. Fat-free-mass emerged as a key determinant in glucose levels across BMI categories, while lower beta-cell function played a significant role in normal-weight women.