Day-to-day glucose variability during pregnancy in women with Type 1 diabetes mellitus: glucose profiles measured with the Continuous Glucose Monitoring System.
OBJECTIVE
To observe day-to-day variability in glucose levels in pregnant women with Type 1 diabetes using the Continuous Glucose Monitoring System (CGMS) and to assess the usefulness of continuous glucose measurements for adjustment of insulin treatment.


METHODS
A prospective observational study.


METHODS
The obstetrical outpatient clinic of the University Medical Centre Utrecht.


METHODS
Pregnant women with Type 1 diabetes mellitus.


METHODS
Thirty-one pregnant women with Type 1 diabetes used the CGMS for two consecutive days. Patients were classified in two groups (high vs low day-to-day variability) based on visual inspection of the glucose excursions. The relationship between day-to-day variability and the variables HbA(1c), maternal age and body mass index (BMI), duration of diabetes, number of self-monitored blood glucose levels, number of insulin injections, gestational age, nutrition, physical activity, White classification, living with children and method of insulin administration was determined. The two days of the first 20 CGMS measurements were separated and four physicians were asked to give recommendations on treatment adjustment for each separate day.


METHODS
Mean absolute difference (MAD) was calculated for each patient as measure of day-to-day variability.


RESULTS
Seventeen patients (55%) were classified as having low (MAD 0.92-2.33 mmol/L) and 14 (45%) as having high day-to-day variability (MAD 2.41-6.12 mmol/L). Of the variables measured, only the relation between MAD and HbA(1c) was significant (r= 0.58, P= 0.001). The difference in recommendation on treatment adjustment between the days of the CGMS measurement ranged from 29% to 48%. This percentage was significantly higher in the high day-to-day variability group (48 vs 33%, P= 0.01).


CONCLUSIONS
Day-to-day glucose variability is high and the treatment of pregnant women with Type 1 diabetes is a problem. Fine-tuning of insulin regimens based on two-day measurements with the CGMS is not advisable.
Kerssen
Anneloes
A
Department of Perinatology and Gynaecology, University Medical Centre Utrecht, KJ.02.507.0, PO Box 80590, 3508 AB Utrecht, The Netherlands.
de Valk
Harold W
HW
Visser
Gerard H A
GH
D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D002940:Circadian Rhythm; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D015444:Exercise; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000097:blood*; D011446:Prospective Studies
D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin