BLOOD SCIENCES
to-processing time, temperature and centrifugation to prevent cellular glycolysis remain relevant to the measured glucose concentration. In routine practice, however, the pre-
analytical pathway is not necessarily identical across every seting. Samples collected in antenatal clinics, hospital phlebotomy departments or community services may have different transport arrangements, processing procedures and time intervals. Even within an individual service, workload and collection schedules can introduce variation. The significance of OPHELIA is that it demonstrates the potential clinical consequences. Women whose GDM was identified only following enhanced processing tended to have a higher BMI and were more likely to have a large- for-gestational-age baby than women diagnosed through standard processing alone. The study therefore suggests that this is not simply a laboratory discrepancy: women with GDM may remain unidentified when glucose samples are not optimally processed. For laboratories, this raises practical questions. How closely are current OGTT pathways monitored against the pre- analytical factors known to affect glucose measurement? How different is the concentration measured in the laboratory from the concentration at blood draw? Collection-to-testing intervals,
transport conditions and time to centrifugation are all potentially auditable components of the pathway. Reviewing these processes locally could help identify variation between collection sites and determine whether existing procedures are sufficiently controlled for a test in which relatively small changes in glucose concentration can alter diagnostic classification. There is also a wider service
implication. More accurate testing may identify more women who require treatment and monitoring, and services need to be prepared for that. But the capacity of the wider pathway should not compromise the quality of the diagnostic process. The fundamental question remains: are we identifying the women who meet the agreed criteria for GDM?
Could the OGTT pathway be redesigned? The question of how the OGTT is delivered is becoming increasingly relevant as healthcare moves towards more accessible and decentralised testing. The conventional OGTT requires a
fasting patient to atend a healthcare seting, undergo repeated blood sampling and remain there for at least two hours. Although this is an established diagnostic
Home and near-patient testing is an opportunity to extend the principles of laboratory medicine beyond the physical laboratory.
pathway, it can create practical barriers for women managing employment, childcare, transport or geographical constraints. The effectiveness of a diagnostic pathway depends not only on the accuracy of the test, but on whether the people who need it can realistically access and complete it. Recent developments in diabetes
technology demonstrate the wider direction of travel. Diabetes UK has highlighted the potential of technology to expand access to glucose monitoring, while NICE has also been developing pregnancy-specific recommendations for diabetes technology. Within GDM, decentralising the OGTT
offers one potential way to address both the pre-analytical challenge and barriers to access, without abandoning the established diagnostic test itself. At Digostics, we have developed
GTT@home to enable the OGTT to be undertaken outside the traditional clinical seting using capillary blood sampling and a connected testing platform. Rather than transporting venous blood back to a laboratory for processing and subsequent analysis, the system enables immediate blood analysis at the point of testing, removing the risk of glucose degradation during transport and processing. The GTT@home managed service is available through the NHS Supply Chain Laboratory Diagnostics, Point-of-Care Testing and Pathology Managed Services Framework. For pathology professionals, moving an
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OGTT outside the conventional laboratory pathway changes how sample collection, measurement and quality assurance need to be considered. A decentralised testing system must demonstrate appropriate analytical performance and method agreement, while quality control and clinical governance all need to be incorporated into the pathway. These requirements are particularly important for GDM because relatively small differences in glucose measurement can affect whether a patient meets a diagnostic threshold.
Maintaining standards The development of home and near- patient testing should not be regarded as a move away from laboratory medicine. It is an opportunity to extend the principles of laboratory medicine beyond the physical laboratory. For pathology services, this means
considering not only whether a device can generate a glucose result, but whether the complete process produces a result that is sufficiently accurate, traceable and clinically meaningful for its intended use. Method comparison, assessment of bias and precision, quality assurance and reliable transfer of results into clinical workflows remain essential regardless of where testing takes place. This is particularly relevant when
considering the findings of OPHELIA. If the pathway before laboratory analysis can materially influence the diagnosis,
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