The Effect of Continuous Glucose Monitoring on Glycemic Control in Insulin-requiring Gestational Diabetes Mellitus

• OBJECTIVES

• To determine if professional CGM improves glycemic control with less hypoglycaemia in insulin- requiring GDM
• To determine if professional CGM use alters management of insulin-requiring GDM
• To determine if professional CGM improves pregnancy outcomes in insulin-requiring GDM.
• To determine patient attitudes toward CGMS.
• HYPOTHESES

• Professional CGMS improves glycaemic control in women with insulin-requiring GDM with less hypoglycaemia
• Professional CGM use will alter management of insulin-requiring GDM
• Professional CGMS will reduce perinatal morbidity and mortality in patients with insulin- requiring GDM
• Third trimester CGMS parameters will correlate better with perinatal outcomes compared with conventional measures of glycaemic control in pregnancy i.e. fructosamine/ A1c/ FBS/ 2hrs PP glucose

STUDY DESIGN

• This is a prospective, open-label, randomized controlled trial. We plan to recruit 80 women with gestational diabetes at 28 weeks gestation or less from the UMMC antenatal clinic. These women should be insulin-naïve but require insulin therapy. 40 subjects (Group 1) will be selected to undergo professional CGM at weeks 28, 32, and week 36 and another 40 subjects individually matched with regards, to age, baseline A1c, BMI will be recruited to undergo usual antenatal care without CGMS (Group 2). The CGMS data will be uploaded and reviewed at weeks 29, 33, and 37 and changes made to the therapeutic regimen as required by the endocrinologist. All mothers will be required to measure their glucose levels at 7 standardized points in a day daily. These glucose readings will be recorded in a diary together with a food log. All subjects will also be required to keep a hypoglycaemia diary.
• The primary outcomes will be glycaemic control in the third trimester and maternal hypoglycaemia. We also plan to assess changes to management made by the endocrinologist based on the additional information on glycemic control obtained from professional CGM use. We also plan to compare hypoglycaemia and hyperglycaemia detection rates using the CGMS and fingerstick methods of glucose evaluation. Patient satisfaction in both groups will also be assessed. Written and informed consent will be obtained in accordance with the principles of the Helsinki Declaration

Inclusion criteria

• women with gestational diabetes
• aged >18 years
• less than or equal to 28 weeks gestation of pregnancy
• singleton pregnancy
• insulin naive , but requiring insulin therapy

Exclusion criteria

• pregestational type 1 or 2 diabetes mellitus
• newly diagnosed overt diabetes in pregnancy ( HbA1c > 6.5)
• hypothyroidism
• Cushing's syndrome/ using exogenous steroids
• chronic infection ( HIV, Hepatitis B/C, Tuberculosis)
• any active chronic systemic disease ( except essential hypertension)
• assisted conception
• pregnancies with fetal anomalies / where imminent or preterm delivery is likely because of maternal disease ( besides gestational diabetes)