Flash Glucose Monitoring in Gestational Diabetes Mellitus: Study Protocol for a Randomized Controlled Trial

Gestational diabetes mellitus (GDM) is glucose intolerance diagnosed for the first time in pregnancy. According to literature GDM affects 3-10% of pregnant women and is a risk factor for multiple maternal and fetal complications. During pregnancy GDM significantly increases the risk of fetal macrosomia, shoulder dystocia, birth trauma and Cesarean section. Furthermore, the long-term complications of GDM include increased risk of development of diabetes mellitus type 2 in the mother, as well as increased risk of obesity, diabetes and metabolic syndrome occurrence in their children. It has been well-documented that the risk of above-mentioned complications increases with the level of maternal hyperglycemia.

Proper glycemia control is one of the key elements in the effective treatment of GDM. Until recently, glucose monitoring was solely performed using glucose meters, which required multiple fingerpricks. Nowadays, due to the glycemia monitoring systems development, such as flash glucose monitoring (FGM), glucose levels may be measured less invasively through subcutaneous sensor application. As shown in one of the studies, FGM due to the ease of use, was 3 times more often applied as a method of glycemia control than SMBG. As a result, patients from FGM group had significantly better blood glucose control.

The main purpose of our study is to evaluate the impact of new method of glycemia control (FGM) on the efficacy of treatment of GDM. By analyzing results of this study, such as mean glycemia levels, number of women requiring insulin therapy and maternal-fetal perinatal outcomes the investigators will provide a scientific basis for more common use of FGM in the population of pregnant women affected by GDM.

This is a randomized controlled trial performed at the 1st Department of Obstetrics and Gynecology of Medical University of Warsaw. The study will recruit 100 women at 24-28 weeks of gestation . Women diagnosed with GDM, who will meet the inclusion criteria, will be individually randomized to Flash Glucose Monitoring (n=50) or Self-Monitoring of Blood Glucose (n=50) group.

The study group will obtain instruction for using Freestyle Libre app to measure and collect glycemia results using a mobile phone.

The control group will be informed about proper use of glucose meters.

All participants will be obliged to measure fasting and 1-h postprandial glucose concentrations in a daily manner, together with once per week midnight measurement.

All participants will obtain dietary recommendations for gestational diabetes mellitus and recommendations about daily physical activity in pregnancy.

In order to assess daily physical activity all participants will obtain a wristband allowing for footsteps measurement.

An evaluation of patient's dietary habits will be based on Eating Assessment Test prepared by the Polish National Institute of Public Health - National Institute of Hygiene.

Clinical and laboratory results of the mother and their newborns will be collected for analysis during the course of pregnancy.

After delivery, at the follow-up visit research staff will retrieve maternal and neonatal outcomes from patients medical history.

Eligibility Criteria:
Inclusion Criteria:

* age ≥ 18 years
* singleton pregnancy between 24-28 weeks of gestation
* gestational diabetes mellitus diagnosis

Exclusion Criteria:

* multiple pregnancy
* fetal malformations
* pre-gestational diabetes mellitus
* chronic or pregnancy-induced hypertension
* chronic renal or hepatic disease, in-vitro fertilization
* delivery \<37 weeks of gestation
* pre-mature rupture of membranes
* placenta previa
* stillbirth
* smoking in pregnancy
* intake of medications including: methyldopa, tetracyclin, acetylosalicylic acid, acetaminofen, ibuprofen, L-dopa, tolazamide, tolbutamide