Introduction: Pre-gestational, type 1 and type 2 diabetes are associated with adverse neonatal outcomes and increased rates of emergency caesarean sections.

Methods: We studied pregnancy outcomes associated with pre-gestational diabetes in 174 women who attended the National Maternity Hospital in Dublin, Ireland, between 2015 and 2017.

Results: Fifty women (28.6%) had type 2 diabetes mellitus, and 124 women (71.4%) had type 1 diabetes mellitus. Women with type 2 diabetes mellitus were older (36 vs. 34 years, p 0.02) and had a higher BMI (32.6 vs. 26.2 kg/m², p 0.00). Duration of diabetes mellitus in type 1 and type 2 was 15.7 and 5.7 years, respectively, and mean HbA1c in type 2 diabetes mellitus at booking was 44.5 mmol/mol (6.2%) and in type 1 diabetes mellitus was 56.3 mmol/mol (7.3%). Forty women (32%) with type 1 diabetes mellitus used continuous subcutaneous insulin infusion. In our cohort, 45.4% had a caesarean delivery. Offspring of patients with multiple dose injections were lighter (3.58 kg) than infants of continuous subcutaneous insulin infusion-treated patients (3.75 kg). More emergency caesarean sections were observed in the continuous subcutaneous insulin infusion group than in the group treated with multiple dose injections (37.5% vs. 28.5%), while the elective caesarean section rate was higher in the multiple dose injection group (17.8% vs. 12.5%). Women treated with continuous subcutaneous insulin infusion had a higher rate of miscarriage (25% vs. 19%) with more congenital malformations (10% vs. 2.3%).

Conclusions: Women in our study with pre-gestational diabetes were overweight, were older and had long-standing diabetes mellitus. Our patients with type 2 diabetes had a higher BMI, were older, had a shorter duration of diabetes mellitus and had better diabetes control compared to women with type 1 diabetes. Women treated with continuous subcutaneous insulin infusion had a higher rate of miscarriage with more congenital malformations. The initial inadequate diabetes control was significantly improved during pregnancy.