Glucose Variability in Pregnancy Complicated by Diabetes

Continuous glucose monitoring (CGM) methods provide details of magnitude and duration of glucose fluctuations, giving a unique insight on daily blood sugar control. Limited data are available on glucose variability (GV) in pregnancy. The aim of this study was to assess GV in normal pregnant women and cases of type 1 diabetes mellitus or gestational diabetes (GDM), and its possible association with HbA1c.

Recent evidence in the literature suggests that glucose variability, characterized by extreme glucose excursions, may overlap with HbA1c levels in determining the risk of diabetes-related complications. Fluctuating blood glucose levels prompt an increase in free radicals and endothelial dysfunction, which are the links between hyperglycemia and the activation of pathological pathways that lead to tissue damage. Reece and Homko postulated an association between maternal hyperglycemia-induced oxygen free radical overproduction and fetal abnormalities, with the onset of diabetes-related embryopathy.Numerous studies have demonstrated that macrosomia and congenital malformations relate to glycemic control. In one study, 48-hour continuous glucose monitoring (CGM) of diurnal glucose profiles in pregnant women with type 1 diabetes was more sensitive than HbA1c alone in identifying an increased risk of offspring with congenital malformations. Such studies give the impression that transient hyperglycemic spikes in pregnant patients with diabetes can cause a high incidence of fetal overweight, regardless of whether or not the mother has chronic hyperglycemia. Glucose variability is still a factor that has been inadequately studied in pregnancies complicated by diabetes, and little is known about its relationship with maternal-fetal outcomes.A number of studies have demonstrated the utility of CGM for monitoring diabetes in pregnancy , but none have focused the attention on the importance of glucose fluctuations during gestation. Meanwhile, there has been a rapid increase in the number of new glucose variability indicators considered, although none of them seems to be definitively reliable. A better understanding of the pattern of blood glucose fluctuations in all the three trimesters of pregnancy, could help us to optimize glycemic control in pregnant women with diabetes. The aim of this study was therefore to assess glucose variability throughout the three trimesters of pregnancy in healthy women and in cases of type 1 diabetes mellitus or gestational diabetes, identifying the more representative and useful indicators of glucose fluctuations, to provide more accurate clinical informations along with HbA1c and beyond.