HbA1c screening reveals 1% may have undiagnosed diabetes
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Using HbA1c testing to screen adults from a large U.K. database revealed approximately 1% had undiagnosed diabetes that was measurable on average 2 years before diagnosis by a health care provider, study data show.
“We realized that the data in UK Biobank gave us a unique opportunity to look at the impact of screening for diabetes in terms of finding the proportion of people with undiagnosed diabetes — as almost all participants had an HbA1c test at recruitment — but also to find how much earlier screening would have identified their diabetes compared with standard clinical care,” Katie Young, PhD, a postdoctoral research associate at University of Exeter Medical School, United Kingdom, told Healio. “The latter was possible because the results of the HbA1c test were not fed back to participants or their doctors, and we had access to their primary care records to find when they actually received a diagnosis from their doctor.”
In the U.K., type 2 diabetes is predominantly diagnosed through HbA1c testing when patients are symptomatic or when they visit their general practitioner for other reasons, Young and colleagues wrote in an abstract presented at the virtual European Association for the Study of Diabetes annual meeting. This can result in a delay between diabetes onset and the start of treatment, increasing the risk for complications; population-level screening could identify these cases earlier and reduce complications.
Young and colleagues analyzed data from 216,644 UK Biobank participants with primary care records available and an HbA1c measured at recruitment. Researchers defined participants without a diagnosis of diabetes at recruitment as those who did not self-report diabetes or had no indications of diabetes in their primary care records before recruitment. For participants with undiagnosed diabetes, researchers calculated the time that it took to receive a clinical diagnosis in their primary care records, defined as the first diagnosis code for diabetes, an HbA1c of at least 48 mmol/mol, or a prescription for glucose-lowering medication.
Within the cohort, 2,022, or 1%, had undiagnosed diabetes on screening by HbA1c. Compared with those with an HbA1c of less than 48 mmol/mol, individuals with an HbA1c of at least 48 mmol/mol on screening were older (mean age, 61 years vs. 58 years; P < .0001), had obesity (mean BMI, 31 kg/m2 vs. 26.6 kg/m2; P < .0001) and were more frequently men vs. women (60% vs. 45%; P < .001).
Of the 82% of participants with undiagnosed diabetes who had primary care records covering the period after recruitment, median time to clinical diagnosis was 2.3 years, with 23% not diagnosed at 5-year follow-up.
“The fact that, on average, screening identified these people 2 years earlier than their doctors was quite surprising to us and suggests that screening could improve patient outcomes by allowing lifestyle interventions and diabetes treatment to begin much earlier,” Young said.
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Young KG, et al. Abstract #331. Presented at: EASD Annual Meeting; Sept. 21-25, 2020 (virtual meeting).
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