Jones DL, Kusinski LC, Barker P, Burling K, Halsall I, Turner E, et al. Enhanced glucose processing in gestational diabetes diagnosis: Effects on health equity and clinical outcomes. Diabet Med. 2024 Dec 17;e15476.
The diagnosis of gestational diabetes mellitus (GDM) has always been a fraught territory. Relying on the oral glucose tolerance test (OGTT), we know the test is inconvenient, variably reproducible, and often poorly tolerated by women. What Jones et al. (2024) add with their OPHELIA study is a careful look at what happens when the pre-analytical handling of blood samples is tightened up: putting samples on ice, rapid centrifugation, and freezing within 2.5 hours. This stops the metabolism of glucose by red cells, leading to. Greater accuracy. The result? Glucose values rise by about 0.6 mmol/L – and the rate of GDM diagnosis leaps from 9% to 22% .
This is an important finding. The additional women picked up weren’t just at the margins. They were, on average, younger, had higher BMIs, and gave birth to significantly more large-for-gestational-age (LGA) infants (37% vs. 22% under standard testing) . In other words, women with clinically meaningful risk were slipping through the diagnostic net when standard processing was used.
The equity dimension
What makes this paper particularly important for those of us in primary care is the way diagnosis intersects with equity. Women most likely to be missed on standard processing were often from higher BMI groups and with differing ethnic profiles. This matters because we already know attendance at OGTT appointments is lower in women from deprived and minoritised ethnic groups . So, the current pathway risks a double inequity: first, some women are less likely to attend, and second, those who do attend may have their hyperglycaemia under-recognised if the sample processing is suboptimal.
As GPs, we often see the knock-on effects of these diagnostic gaps. Babies born large-for-gestational-age, women with unrecognised hyperglycaemia who may face higher risks of future type 2 diabetes, and families who shoulder the longer-term metabolic consequences.
But what about overdiagnosis?
Of course, increasing the diagnosis rate so dramatically raises another concern: are we at risk of overmedicalising pregnancy? Some women identified by enhanced processing required no treatment beyond lifestyle advice, and their risk profile was arguably milder. Jones et al. acknowledge this, but importantly they found the undiagnosed group were not uniformly “low risk” – they had comparable fasting glucose levels to the standard GDM group and higher rates of adverse outcomes.
For primary care, this tension between under- and over-diagnosis is familiar territory. Just as with hypertension thresholds or cholesterol risk calculators, the line between early intervention and unnecessary burden is a fine one. The challenge will be whether health systems can support the increase in GDM diagnoses with proportionate and person-centred management, without overwhelming services or fuelling unnecessary anxiety in women.
Implications for practice
For GPs, the study prompts some key reflections:
Equity of access: If enhanced processing becomes standard, are we simultaneously addressing the barriers that keep some women from being tested in the first place? Otherwise, the inequity gap may actually widen. Holistic risk framing: Enhanced processing identifies women at higher risk of adverse outcomes – but diagnosis alone isn’t the endpoint. Supporting women through diet, activity, and psychosocial support may be more impactful than simply labelling. The long view: Diagnosing GDM is not just about pregnancy outcomes. It’s also about recognising long-term metabolic risk and ensuring women get follow-up beyond the six-week postnatal check.
Ultimately, this paper reinforces a core truth: how we handle samples in the lab isn’t a technicality – it shapes who gets a diagnosis, who gets treatment, and who carries risk unnoticed. If we are serious about tackling health inequities in pregnancy, then perhaps the starting point is as simple (and as complex) as a tube of blood and some ice.
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