Introduction: Glycemic control has a major effect on fetal growth in women with type 1 diabetes mellitus (DM1), worse control leading to increased growth (large for gestational age (LGA) or very large for gestational age (VLGA) fetus). Currently, we aim at strict control (at least HbA1c ≤ 48 mmol/mol) before and during pregnancy. Real Time Continuous Glucose Monitoring (RTCGM) offers new ways to achieve this. We performed a retrospective chart review of pregnancy outcomes in DM1 to assess outcome and CGM-data in well-controlled women with DM1.

Methods: Forty-eight pregnancies in 25 women were identified between 2016-2019; 19 women with a singleton pregnancy met the inclusion criterion of HbA1c ≤ 48 mmol/mol in 1st and 3rd trimester; 8 women had insufficient CGM-data.; CGM could be analysed in 11 women. LGA was defined as fetal weight > 90th and VLGA > 97.7th percentile. CGM-data were studied during 4 periods: 4-8 weeks gestation, 18-22 weeks, 30-34 weeks and last 8 days before delivery. Target range 3.5-7.8 mmol/L. Time in range (TIR), time below range (TBR) and time above range (TAR) were calculated.

Results: In the 19 women with adequate control, LGA (LGA and VLGA) in 36.8%; simple LGA 15.7%, VLGA 21.1%. There were no congenital malformations. Women with VLGA child were significantly older (p<0.03), had higher BMI (p<0.02) and longer duration of DM1 (p<0.02). In women with normal growth fetus, LGA or VLGA, Time In Range (TIR) was 64.1%, 63.6% and 58.5%; Time Above Range (TAR): 24.4, 34.4 and 39.6%; Time Below Range: 4.0, 2.2 and 2.1%.

Conclusion: Our data show that current implementation of advanced technology was associated with mean TIR below recommended level of >70% and TAR above recommended level (<25%). Prevalence of LGA and VLGA was still increased. Adaptation of care and counselling re needed for improvement in outcome with technology.


H.W. de Valk: None. L. Oosterwijk: None. K. Kaasjager: None.

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