Comparing the different phenotypes of diabetes in pregnancy: are outcomes worse for women with young-onset type 2 diabetes compared to type 1 diabetes?

Aims: Pregnancies are increasingly affected by young-onset type 2 diabetes mellitus (YT2DM), an aggressive phenotype associated with a higher vascular risk profile compared to type 1 diabetes mellitus (T1DM). We compared pregnancy outcomes to illuminate areas where differing management guidance might be needed. 

Methods: This retrospective single-centre study (2010 2019) included 259 singleton pregnancies affected by pregestational T1DM (N = 124) or YT2DM (N = 135) diagnosed at < 40 years. Primary outcomes included preterm delivery, large for gestational age (LGA) infants, and pre-eclampsia. Results: The YT2DM cohort were older, with more obesity, greater apparent sociodemographic disadvantage, and lower measures of pregnancy preparedness. Overweight/obesity were also prevalent in the T1DM cohort (46 % affected). The second/third trimester mean HbA1c measurements were significantly higher in the T1DM cohort. Pre-eclampsia and preterm delivery rates were similar between the cohorts. Significantly lower rates of LGA infants, NICU admission, neonatal hypoglycaemia, and neonatal respiratory distress were seen in the YT2DM cohort (p < 0.05 for all). 

Conclusions: In pregnancy, YT2DM appears to be the lower-risk cohort compared to T1DM despite higher obesity rates. Gaps in achieving glycaemic targets exist for both subtypes but particularly for T1DM. The relative impact of increasing BMI in pregnancies affected by T1DM requires further elucidation.