Objective: To compare Continuous Glucose Monitoring System (CGMS) with self-monitoring of plasma glucose (SM) in detecting patients with gestational diabetes mellitus (GDM) needing antidiabetic drug treatment.
Research design and methods: Pregnant women at 22-34 gestational weeks had at least two abnormal high values out of three in OGTT. Patients were randomly allocated to have CGMS) (n=36) or SM (n=37). Dietary counselling was similar in both groups. Patients tested their plasma glucose 5 times per day. Need of antidiabetic treatment was determined using the following cut-off values: fasting plasma glucose >5.5mmol/L twice or >5.5mmol/l once and postprandial value>7.8mmol/l, or postprandial value at least twice above 7.8mmol/l.
Results: In 11 out of 36 patients (31%) monitored with CGMS) antihyperglycemic drug therapy was introduced (8/36 insulin only, 2/36 metformin only, 1/36 insulin+metformin) whereas only 3/37 (8%) in the self-monitoring group were drug-treated (difference between groups, p=0.0149). There were no statistically significant differences between the groups regarding maternal age, pre-pregnancy BMI, HbA1c, gestational weeks at delivery, rate of pregnancy-induced hypertension, rate of caesarean section, infant birth weight or neonatal hypoglycaemia.
Conclusions: Continuous glucose monitoring system detects a markedly higher proportion of GDM mothers needing antihyperglycemic medication compared with self-monitoring of plasma glucose. Further large-scale studies are needed to evaluate whether CGMS) guided initiation of antihyperglycemic therapy results in less macrosomia and perinatal complications related to GDM.