Objective: To assess the detection rate of hyperglycemia with a continuous glucose monitoring system compared to a self-monitoring blood glucose profile in non-pregnant, non-diabetic pregnant women, and patients with impaired glucose tolerance or gestational diabetes..
Methods: Eight non-pregnant (NP) and 56 pregnant women (17 dietary-treated gestational diabetics (GDM), 15 women with impaired glucose tolerance (IGT), and 24 non-diabetic pregnant women (NDP)) underwent a 72-hour measurement with the CGMS (Medtronic Minimed, Northridge, CA, USA). Self-monitored blood glucose measurements, performed 30 minutes before and 120 minutes after each meal, were compared to the duration of hyperglycemia monitored by the continuous glucose monitoring system.
Results: No clinically observable infection was found at the subcutaneous tissue where the electrode was placed. A statistically significant difference was found between the groups in body mass index, HbA1c, and in gestational age, but not in age or parity. Using the self-monitored blood glucose (SMBG), 88 % (7/8) of the NP and 54 % (13/24) of the NDP had no measurement above 6.7 mmol/l. However, 17 % (4/24) of the NDP and 40 % (6/15) of the IGT showed more than two measurements above 6.7 mmol/l compared to 24 % (4/17) of the dietary-treated GDM. The differences between these groups were not significant (p = 0.21). The mean durations (+/- SD) of hyperglycemia above 6.7 mmol/l/24 h were: NP 111 +/- 120 min, NDP 138 +/- 120 min, IGT 381.8 +/- 295 min, and GDM 190 +/- 155 min, p = 0.017; above 7.8 mmol/l/24 h NP 24 +/- 49 min, NDP 38 +/- 47 min, IGT 170.7 +/- 190 min, and GDM 64 +/- 88 min, p = 0.016; and above 8.9 mmol/l/24 h NP 9.3 +/- 25 min, NDP 7.5 +/- 14 min, IGT 59 +/- 77 min, and GDM 14 +/- 21 min, p = 0.026. There was no significant difference in the fetal outcome or rate of birth percentiles using the sensor data.
Conclusions: The use of the sensor in pregnant women is unproblematic. a) The CGMS detected more frequent and longer durations of hyperglycemia in GDM compared to non-diabetic pregnant women than the SMBG. b) Women with an IGT exhibited higher glucose levels than patients with gestational diabetes. c) The clinical importance of these hyperglycemic intervals, e.g. with respect to the risk for macrosomia, must be assessed in larger trials.