Continuous glucose monitoring boosts glycaemic control in diabetic pregnant women

Continuous glucose monitor (CGMs) devices fitted with automatic insulin delivery could help improve glycaemic control in pregnant women with type 1 diabetes mellitus (T1DM), according to a recent study.

“In our present study, we evaluated the role of CGM technology in the management of T1DM in women during pregnancy,” the researchers said. “We observed that the use of CGM was associated with lower glycated haemoglobin (HbA1c) levels during pregnancy and this lasted for some time after delivery.”

The researchers conducted an observational, single-centre study involving 81 women with T1DM who were pregnant or planning pregnancy. Participants were offered combinations of insulin delivery and glucose monitoring systems: 28 eventually chose to take continuous subcutaneous insulin infusions (CSII) with CGM, 42 CSII without CGM, and 11 multiple daily injections (MDI).

Throughout the pregnancies, the researchers assessed for the following endpoints: HbA1c concentration and changes over time, maternal weight gain, birth weight, and the frequency of macrosomia or preterm deliveries, among others.

The CGM device allowed for superior glucose control almost immediately, though not significantly so. HbA1c levels at first follow-up were 5.6 percent in the CSII-CGM group, as opposed to 6.0 percent and 6.2 percent in the CSII-no CGM and MDI groups, respectively (p=0.149). Baseline HbA1c levels were comparable across all three groups. [Ginekol Pol 2021;doi:10.5603/GP.a2021.0029]

During the first, second, and third trimesters, women on CSII and CGM had the lowest HbA1c levels, at 5.3 percent, 5.3 percent, and 5.2 percent, respectively. Compared to those not using CGM or were on MDI, these concentrations were significantly lower (p=0.003, p=0.003, and p=0.039, respectively).

Three to six months after pregnancy, HbA1c in the CGM mothers increased slightly to 5.5 percent, but nevertheless remained significantly lower than the other two comparator groups (p=0.002).

In addition, women using devices with the predictive low-glucose suspend (PLGS) functionality achieved a significantly lower HbA1c level by the third trimester compared with other CSII patients with or without CGM (p=0.044). This effect persisted until after pregnancy (p=0.016).

In terms of birth outcomes, the researchers detected no significant impact of device use on birthweight, duration of pregnancy, gestational age at delivery, or macrosomia.

Eight congenital malformations occurred in the cohort, including five cases of heart abnormalities, two of genetic syndromes, and one of congenital limb defect. No stillbirths or early hospital deaths were recorded.

“In this study, we attempted to compare the use of pumps augmented with CGM versus the use of pumps without CGM and MDI regimen,” the researchers said.

The observational study design does not allow for any firm conclusions; however, there was a clear trend towards better glycaemic control among the users of insulin pumps with CGM, they added.