Background:

Gestational diabetes mellitus (GDM) increases the risk of obstetric and neonatal complications (1). While Continuous Glucose Monitoring (CGM) is the standard of care in Type 1 Diabetes in pregnancy, its role in GDM is developing. The 2026 international consensus guidelines recommend CGM as an adjunct to self-monitoring of blood glucose (SMBG) however management guidance when CGM is used in the absence of SMBG is not provided (2).

Clinical Case:

A 39-year-old female (G3P1) was diagnosed with GDM via a 75g OGTT at 27 weeks. The patient self-funded CGM to reduce testing burden, however, while CGM provided a high volume of continuous data, the standard Ambulatory Glucose Profile (AGP) lacks the temporal granularity to isolate discrete two-hour postprandial values.  In order to manage her GDM according to the national GDM glycaemic targets, a strategy to interpret the CGM data was needed.

To address this, a structured protocol was implemented: active sensor scanning when fasting and exactly 2 hours post-prandially, with data uploaded to the service’s standard digital platform (Net-Health). This enabled isolation of discrete fasting and post-prandial levels, facilitating precise insulin titration. This workable solution not only streamlined clinical decision-making but also fostered greater patient engagement and self-management. After implementation of this protocol, it resulted in a measurable improvement in glycaemic control. CGM identified occult nocturnal dysglycaemia undetected by SMBG.

Literature Review: While CGM improves maternal glycaemic control in GDM by maintaining TIR and reducing GV, evidence for improved neonatal outcomes remains limited (3,4). The GRACE open-label RCT reported lower LGA incidence and birthweight percentiles with CGM, however, this was accompanied by a higher SGA incidence, potentially due to overtreatment (5). Adequately powered studies are needed to establish definitive clinical efficacy.

Conclusion: The 2026 Consensus suggests a TIR target of >90% (3.5-7.8 mmol/L) (2). However, until evidence based guidance for GDM management using CGM alone exists, scanning and recording glucose levels at standardised times allows for the application of validated treatment thresholds in a non-invasive manner (6). Management can then be finessed utilising the additional data CGM provides.