Longitudinal changes in the continuous glucose profile measured by the CGMS ® in healthy pregnant women and determination of cut-off values

Abstract

Objective This longitudinal study performed continuous evaluation of daily blood glucose level profiles in healthy normal-weight pregnant patients during various gestational age and determined normal levels. Study design Thirty-two healthy normal-weight pregnant women received a continuous glucose monitoring system (CGMS ®) device for periods of 72 h in the 16th, 22nd, 30th and 36th weeks of gestational age and at 6 weeks after delivery. All observations took place in the outpatient clinic of the Charité hospital. The daily blood glucose level profiles obtained with the CGMS provided pre- and postprandial blood glucose levels and a mean glucose value for a 24-h period. Caloric intake was determined using detailed food logs. Additionally, a fetal biometry and an measurement of maternal weight were performed at each visit. The correlation was tested using Spearman's test. Results The average age of the study subjects was 29.6 ± 4.5. Average pre-pregnancy BMI was 22.4 ± 2.5 kg/m 2. The births occurred on average in the 40th week of pregnancy. Average caloric intake was 2223 ± 356 kcal. No significant changes in caloric intake were observed during the course of the study. The blood glucose levels showed a significant rise throughout the course of the pregnancy, going from 4.84 ± 0.4 mmol/l (87.2 ± 7.2 mg/dl) during the 30th week of pregnancy to 5.22 ± 0.5 mmol/l (94.0 ± 9.0 mg/dl) during the 36th week ( p = 0.002). Postpartum levels were 5.20 ± 0.5 mmol/l (93.7 ± 9.0 mg/dl) ( p = 0.51). Fasting blood glucose levels did not change during the course of the pregnancy. A noticeable aspect were the significantly increased fasting postpartum levels with 5.02 ± 0.6 mmol/l (90.4 ± 10.8 mg/dl) ( p = 0.00). Analysis of the postprandial glucose levels confirmed a rise from 5.30 ± 0.6 mmol/l (95.5 ± 10.8 mg/dl) in the 16th week to 6.14 ± 0.7 mmol/l (110.6 ± 12.6 mg/dl) in the fourth study phase (36th week), and a decrease after the birth to 5.59 ± 0.6 mmol/l (100.7 ± 10.8 mg/dl). These measurements were adapted to the gestational age. Conclusion Continuous measured glucose levels rose during the pregnancy in healthy pregnant women in spite of normal pre-pregnancy metabolism and unchanged carbohydrate intake during gestation. These results suggest the necessity of gestational-age-dependent cut-off values.