Gestational diabetes mellitus (GDM) is an intolerance of carbohydrates diagnosed in the second or third semester of pregnancy, with no clear evidence of previous diabetes mellitus.1 It is prevalent in about 8.8% of total gestations (1%–12%).2 Hyperglycemia in pregnancy is related to greater risk of maternal complications (hypertension induced by pregnancy, pre-eclampsia, intrauterine fetal death, caesarean section birth) and fetal complications (hypoglycemia, hyperbilirubinemia, macrosomia, obstetric traumatism).3 In addition, it involves a greater risk of developing type 2 diabetes mellitus (DM) and metabolic syndrome with an increase in incidence of cardiovascular diseases.4, 5

GDM treatment aims to maintain glycemia levels within a very narrow range similar to that of gestation without diabetes. It includes hygienic dietary measures and, if these have no effect, pharmacological treatment.6

In common clinical practice, glucose levels are measured by self-monitoring of capillary glycemia (SMCG), however, nowadays continuous glucose monitoring (CGM) systems can measure the glucose of the interstitial fluid using an electrochemical method that makes a good correlation between the glucose calculated at interstitial level and in the blood.7 There are also real-time, blind or retrospective sensors, the latter used by professionals as a diagnostic-therapeutic tool to modify DM patients’ treatment.8

Studies using CGM are rare in GDM, involving few patients and frequently analyzing them alongside women with both pre-gestational and gestational DM. Nevertheless, these few studies have shown that CGM systems detect hyperglycemia more frequently than SMCG.9, 10 Also, the use of both real-time and retrospective CGM is associated to better glycemia control than when SMCG is applied, and to less weight gain in both mother and newborn. Yet there is no evidence of a reduction in other maternal-fetal complications related to GDM.11, 12 Recent years have seen an increase in the study of GV parameters using CGM, describing higher GV in women with GDM.13, 14 However, in the retrospective use of CGM in GDM, the GV data obtained as a predictive tool for the onset of obstetric and perinatal complications have provided mixed results.15

In GDM treatment, hygienic dietary measures have been shown to reduce excess weight in newborns, and there has been a drop in maternal-fetal complications when pharmacological treatment is administered.16, 17, 18 In terms of CGM in GDM and pharmacological treatment, some studies have shown that when CGM is used, more patients start pharmacological treatment than when only SMCG is used.19 However, so far no study has analyzed the use of CGM following GDM diagnosis to detect GV parameters and their relation to the probability of requiring pharmacological treatment.

The aim of our study was to use CGM, on diagnosis of GDM, to establish whether mean glycemia levels and GV parameters can help predict the probability of a patient requiring pharmacological treatment, and whether these parameters are related to the development of obstetric and perinatal complications.