Continuous glucose monitoring for the evaluation and improved control of gestational diabetes mellitus

OBJECTIVES: To compare the daily glycemic profile reflected by continuous versus self-monitoring of blood glucose in women with gestational diabetes mellitus (GDM), and to evaluate possible differences in treatment strategy based on the two monitoring methods. MATERIALS AND METHODS: The study sample consisted of 57 women with gestational diabetes, 47 in Israel and ten in California. Gestational age ranged from 24 to 32 weeks in the Israeli women, and 32 to 36 weeks in the American women. Data derived from the Continuous Glucose Monitoring (CGM) System (MiniMed) for 72 h were compared to fingerstick glucose measurements (6-8 times a day). During continuous monitoring, patients documented the timing of food intake, insulin injections and hypoglycemic events. RESULTS: In the Israeli group, 23 women were treated by diet alone, and 24 by diet plus insulin. An average of 763 +/- 62 glucose measurements was recorded for each patient with continuous glucose monitoring. The mean total time of hyperglycemia (glucose level > 140 mg/dl) undetected by the fingerstick method was 132 +/- 31 min/day in the insulin-treated group and 94 +/- 23 min/day in the diet-treated group. Nocturnal hypoglycemic events (glucose levels < 50 mg/dl) were recorded in 14 patients, all insulin-treated. On the basis of the additional information provided by continuous monitoring, the therapeutic regimen (insulin therapy, diet adjustment, or both) was changed in 36 of the 47 patients. All ten American women were treated with insulin. The mean time of undetected hyperglycemia for a total group monitoring time of 30 days was 78 +/- 13 min/day. Eight women had nocturnal hypoglycemia on at least one of the three nights of monitoring for a total of 12 nights. A change in insulin dosage was made in all women on the basis of the data provided by continuous glucose monitoring. CONCLUSION: Continuous glucose monitoring is helpful for monitoring women with GDM and for adjusting diabetes therapy. It can accurately detect high postprandial blood glucose levels and nocturnal hypoglycemic events that may go unrecognized by intermittent blood glucose monitoring. A large prospective study on maternal and neonatal outcome is needed to determine the clinical implications of this new monitoring technique.