How accurate are non-invasive and minimally invasive glucose monitoring devices for detecting of hypoglycaemia?

Problem

Minimally and non-invasive monitoring devices (including continuous glucose monitoring and flash glucose monitoring) have evolved rapidly over recent years and an increasing number of patients using those devices are seen in primary care. While many manufacturers advertise the safety and convenience with which their devices warn of hypoglycaemic episodes, there is no clear evidence on how accurately they can actually detect hypoglycaemia. To address this question, we assessed systematically the diagnostic accuracy of minimally and non-invasive hypoglycaemia detection in comparison to capillary or venous blood glucose in patients with Type 1 or Type 2 diabetes.

Approach

Clinical Trials.gov, Cochrane Library, Embase, PubMed, ProQuest, Scopus and Web of Science were systematically searched. Two authors independently screened the articles, extracted data using a standardised extraction form and assessed methodological quality using an established quality assessment tool for diagnostic accuracy studies (QUADAS-2). A meta-analysis was performed to assess diagnostic accuracy of hypoglycaemia using a bivariate random effects model. The effect of pre-specified co-variates was analysed using meta-regression. Systematic review registration: PROSPERO 2018 CRD42018104812.

Findings

We identified 3416 nonduplicate articles. Finally, 15 studies with a total of 733 patients were included. Different thresholds for hypoglycaemia detection ranging from 40 to 100 mg/dl were used. The most common threshold was 70 mg/dl. Pooled analysis revealed a relatively poor mean sensitivity of 69.3% [95% CI: 56.8 to 79.4] and a mean specificity of 93.3% [95% CI: 88.2 to 96.3]. Meta-regression analyses showed better hypoglycaemia detection of minimally invasive devices as compared to non-invasive devices. Furthermore, in studies indicating a higher overall accuracy and in studies funded by manufacturers pooled sensitivity was significantly higher. Finally, we saw a notable rate of side effects and adverse events and a limited sensor stability.

Consequences

The present data suggest that minimally and non-invasive monitoring systems are not sufficiently accurate for detecting hypoglycaemia in routine use. Primary care physicians have to be aware of this limitation when communicating with individuals interested in or using those devices.