CONCEPTT: CGM during pregnancy in T1D cuts neonatal complications
Adding continuous glucose monitoring (CGM) to conventional finger-prick test during pregnancy increases the time spent in the recommended glycaemic target range and improves neonatal health outcomes in patients with type 1 diabetes (T1D) compared with traditional test alone, according to the CONCEPTT* study presented at EASD 2017.
“Our data indicate a role for offering CGM to all pregnant women with T1D using intensive insulin therapy in the first trimester,” suggested the researchers.
The multicentre, open-label trial enrolled 325 women (aged 18–40 years) who had T1D for at least 1 year and were receiving intensive insulin therapy. Of the participants, 215 were pregnant women (≤13 weeks and 6 days’ gestation) and 110 were women planning pregnancy who were randomized to capillary glucose monitoring plus CGM or capillary glucose monitoring alone. [EASD 2017, session S42; Lancet 2017;doi:10.1016/S0140-6736(17)32400-5]
Among the pregnant participants, CGM led to more time spent in glycaemic target than the capillary glucose monitoring alone (68 percent vs 61 percent; p=0.0034), with less time being hyperglycaemic (27 percent vs 32 percent; p=0.0279). This, according to the researchers, translates to “an additional 1.7 h/day in target” and “approximately 1 h less per day spent hyperglycaemic”.
However, time spent being hypoglycaemic (3 percent vs 4 percent; p=0.10) and severe hypoglycaemia episodes (18 vs 21) were comparable between the two treatment groups.
There was a small but significant difference in HbA1c between the CGM and the control groups (-0.19 percent; p=0.0207), although this did not meet the prespecified primary endpoint of a 0.5 percent difference between groups.
“The results were consistent across 31 international study sites and comparable for women using insulin pumps or multiple daily injections, regardless of baseline glucose control,” observed the researchers. “The finding that the treatment effect of CGM is comparable between pump and injection users is very important for widening access to technology.”
Significant improvements in neonatal outcomes were also observed with CGM vs control, including reductions in risks of large for gestational age (odds ratio [OR], 0.51; p=0.0210), neonatal intensive care unit (NICU) admissions of >24 h (OR, 0.48; p=0·0157), and neonatal hypoglycaemia requiring intravenous treatment (OR, 0.45; p=0.0250). Length of hospital stay was also shorter in the CGM vs the control groups (p=0.0091).
“The odds ratios of having the main neonatal events were reduced by approximately 50 percent between groups,” said lead author Dr Denise Feig from Sinai Health System in Toronto, Canada, to which study co-investigator and copresenter Prof Helen Murphy, also from Sinai Health System, suggested, “[The] improved outcomes would be attributed to reduced exposure to maternal hypoglycaemia.”
“The number needed to treat [NNT] was very low ... which suggests there could be potential for cost savings. Formal health economic analysis is under way,” said Murphy, noting that the NNTs to prevent one NICU admission or one large for gestational age were both six and the NNT to prevent one case of neonatal hypoglycaemia was eight.
“[On the other hand,] we found no consistent benefit of CGM in women planning pregnancy,” she added.
Adverse events were more common in the CGM than the control groups (48 percent vs 40 percent in the pregnant cohort), with skin reactions being the most common event (48 percent vs 8 percent). Few serious adverse events occurred, with comparable rates between the two treatment groups and gastrointestinal (nausea and vomiting) occurring most frequently.
Also, more participants reported frustrations with CGM use, with 80.6 percent encountering problems such as connectivity issues and calibration errors, compared with 12.5 percent in the control group.
In a response to whether one will implement CGM to all pregnant women with T1D, invited commentator Prof Elisabeth Mathiesen of Rigshospitalet University Hospital in Copenhagen, Denmark, said, “Better HbA1c is already obtained in our centre, with lower rate of preterm delivery and overweight newborns … The cost [with CGM] will prompt a reduction in other aspects of the care of pregnant women.”
At the same time, she was also optimistic that “many women will ask for it, and this study supports its use, and my gut feeling is that CGM is the future.”