Sensor-derived glycaemic metrics in pregnant women with type 1 diabetes randomised to faster acting insulin aspart or insulin aspart-A secondary analysis of the CopenFast trial.

Aims: We compared sensor-derived glycaemic metrics in pregnant women with type 1 diabetes (T1D) randomised to faster acting insulin aspart (faster aspart) or insulin aspart (IAsp).

Methods: A pre-planned secondary analysis of the CopenFast trial included women with T1D using intermittently scanned continuous glucose monitoring (isCGM) during pregnancy. Glycaemic metrics, including time in range (TIRp, 3.5-7.8 mmol/L) and time below range in pregnancy (TBRp, <3.5 mmol/L), were evaluated in the intervals: from randomisation (median 9.5 weeks, interquartile range 9.0-11.0) to 21 weeks, from 22 to 33 weeks and from 34 to 37 weeks.

Results: In total, 113 (91%) of 124 women using isCGM in the original trial were included. At randomisation, glycaemic metrics were comparable in both groups. Women randomised to faster aspart achieved higher TIRp from 22 to 33 weeks (estimated treatment difference 5.1% [95% confidence interval 0.3; 9.7], p = 0.04) and mean TIRp >70% from randomisation to 21 weeks onwards, while this was achieved after 34 weeks in women randomised to IAsp. TBRp remained stable around 4% throughout pregnancy in both groups. One (2%) versus 5 (9%) experienced ≥1 severe hypoglycaemic event (odds ratio 0.93 [-0.2; -0.01], p = 0.04). Infant birthweight standard deviation score was lower in the faster aspart group (estimated treatment difference -0.5 [-0.9; -0.03], p = 0.04); however, this attenuated when adjusting for parity (p = 0.10).

Conclusions: Women using faster aspart achieved more TIRp and experienced less severe hypoglycaemia compared to women using IAsp. Infant birthweight was lower and thereby more appropriate in the faster aspart group; however, this attenuated when adjusting for parity.