Real-time continuous glucose monitoring as a tool to prevent severe hypoglycaemia in selected pregnant women with Type 1 diabetes - an observational study.

AIMS: Among women with Type 1 diabetes who have had severe hypoglycaemia the year before pregnancy, 70% also experience this complication in pregnancy, and particularly in the first half of pregnancy. We evaluated whether routine use of real-time continuous glucose monitoring from early pregnancy onwards could prevent severe hypoglycaemia in these women.

METHODS: All 136 consecutive pregnant women with Type 1 diabetes referred to our centre were asked about severe hypoglycaemic events in the year before pregnancy and early in pregnancy at their first antenatal visit. Women with a relevant recent history were informed about their additional high risk of severe hypoglycaemia, their treatment was focused on restricted insulin doses during the first 16 gestational weeks, and they were offered real-time continuous glucose monitoring on top of self-monitored plasma glucose measurements.

RESULTS: Among 28 women with a recent history of severe hypoglycaemia, 12 (43%) used real-time continuous glucose monitoring from a median (range) of 10 (7-13) gestational weeks for 10 (1-32) weeks. Among these 12 women, eight had experienced a total of 34 (range 1-11) severe hypoglycaemic events in the year before pregnancy and nine had experienced 23 (range 1-10) events early in pregnancy. After initiation of real-time continuous glucose monitoring, two (17%) women experienced one event each. The incidence rates of severe hypoglycaemia were 2.8,17.5 and 0.3 events/patient-year. Among the 16 women in the high risk group not using real-time continuous glucose monitoring, the corresponding figures were 1.6, 5.0 and 0.1 events/patient-year.

CONCLUSIONS: Further evaluation is required to determine whether continuous real-time continuous glucose monitoring from early pregnancy onwards in highly selected women may reduce the risk of severe hypoglycaemia. Other elements of focused intervention probably also contribute to the risk reduction.