Aims: To determine if therapeutic, retrospective continuous glucose monitoring (CGM) improves HbA1c with less hypoglycaemia in women with insulin-treated gestational diabetes mellitus (GDM).
Methods: This prospective, randomized controlled, open-label trial evaluated 50 women with insulin-treated GDM randomized to either retrospective CGM (6-day sensor) at 28, 32 and 36 weeks' gestation (Group 1, CGM, n = 25) or usual antenatal care without CGM (Group 2, control, n = 25). All women performed seven-point capillary blood glucose (CBG) profiles at least 3 days per week and recorded hypoglycaemic events (symptomatic and asymptomatic CBG < 3.5 mmol/l; non-fasting < 4.0 mmol/l). HbA1c was measured at 28, 33 and 37 weeks. In Group 1, both CGM and CBG data were used to manage diabetes, whereas mothers in Group 2 were managed based on CBG data alone.
Results: Baseline characteristics (age, pre-pregnancy BMI, HbA1c , total insulin dose) were similar between groups. There was a lower increase in HbA1c from 28 to 37 weeks' gestation in the CGM group [∆HbA1c : CGM + 1 mmol/mol (0.09%), control + 3mmol/mol (0.30%); P = 0.024]. Mean HbA1c remained unchanged throughout the trial in the CGM group, but increased significantly in controls as pregnancy advanced. Mean HbA1c in the CGM group was lower at 37 weeks compared with controls [33 ± 4 mmol/mol (5.2 ± 0.4%) vs. 38 ± 7 mmol/mol (5.6 ± 0.6%), P < 0.006]. Some 92% of the CGM group achieved an HbA1c ≤ 39 mmol/mol (≤ 5.8%) at 37 weeks compared with 68% of the control group (P = 0.012). Neither group experienced severe hypoglycaemia.
Conclusion: CGM use may be beneficial in insulin-treated GDM because it improves HbA1c compared with usual antenatal care without increasing severe hypoglycaemia. (Clinical Trials Registry No.: NCT02204657).
© 2018 Diabetes UK.