Closed-loop systems use a
computer algorithm (a set of mathematical instructions)
to adjust insulin-pump delivery in response
to glucose measurements obtained from
real-time continuous glucose monitors.14 These
systems have been shown to improve glycemic
control without increasing the risk of hypoglycemia
under experimental conditions,15-17 in trials
of supervised outpatient treatment,18-22 and in
studies of unsupervised, self-administered treatment
among patients who were not pregnant.23-25
Preliminary data suggest that closed-loop systems
may maintain near-normal glucose levels and
minimize the risk of nocturnal hypoglycemia
among pregnant women with type 1 diabetes.26,27
We performed a 4-week, randomized, crossover
study of an overnight closed-loop system, followed
by a 14-week continuation phase of dayand-night
closed-loop therapy, which encompassed
pregnancy-related challenges, including
antenatal hospital admission, labor, and delivery,
as well as postnatal adaptation.