Rodgers Lauren R, Hill Anita V, Dennis John M, Craig Zoe, May Benedict, Hattersley Andrew T, McDonald Timothy J, Andrews Rob C, Jones Angus, Shields Beverley M
Institute of Health Research, University of Exeter Medical School, South Cloisters, St Lukes Campus, Exeter, EX1 2LU, UK.
NIHR Exeter Clinical Research Facility, Royal Devon & Exeter NHS Foundation Trust & University of Exeter Medical School, Exeter, UK.
BMC Med. 2021 Aug 20;19(1):184. doi: 10.1186/s12916-021-02054-w.
Type 2 diabetes (T2D) is common and increasing in prevalence. It is possible to prevent or delay T2D using lifestyle intervention programmes. Entry to these programmes is usually determined by a measure of glycaemia in the 'intermediate' range. This paper investigated the relationship between HbA1c and future diabetes risk and determined the impact of varying thresholds to identify those at high risk of developing T2D.
We studied 4227 participants without diabetes aged ≥ 40 years recruited to the Exeter 10,000 population cohort in South West England. HbA1c was measured at study recruitment with repeat HbA1c available as part of usual care. Absolute risk of developing diabetes within 5 years, defined by HbA1c ≥ 48 mmol/mol (6.5%), according to baseline HbA1c, was assessed by a flexible parametric survival model.
The overall absolute 5-year risk (95% CI) of developing T2D in the cohort was 4.2% (3.6, 4.8%). This rose to 7.1% (6.1, 8.2%) in the 56% (n = 2358/4224) of participants classified 'high-risk' with HbA1c ≥ 39 mmol/mol (5.7%; ADA criteria). Under IEC criteria, HbA1c ≥ 42 mmol/mol (6.0%), 22% (n = 929/4277) of the cohort was classified high-risk with 5-year risk 14.9% (12.6, 17.2%). Those with the highest HbA1c values (44-47 mmol/mol [6.2-6.4%]) had much higher 5-year risk, 26.4% (22.0, 30.5%) compared with 2.1% (1.5, 2.6%) for 39-41 mmol/mol (5.7-5.9%) and 7.0% (5.4, 8.6%) for 42-43 mmol/mol (6.0-6.1%). Changing the entry criterion to prevention programmes from 39 to 42 mmol/mol (5.7-6.0%) reduced the proportion classified high-risk by 61%, and increased the positive predictive value (PPV) from 5.8 to 12.4% with negligible impact on the negative predictive value (NPV), 99.6% to 99.1%. Increasing the threshold further, to 44 mmol/mol (6.2%), reduced those classified high-risk by 59%, and markedly increased the PPV from 12.4 to 23.2% and had little impact on the NPV (99.1% to 98.5%).
A large proportion of people are identified as high-risk using current thresholds. Increasing the risk threshold markedly reduces the number of people that would be classified as high-risk and entered into prevention programmes, although this must be balanced against cases missed. Raising the entry threshold would allow limited intervention opportunities to be focused on those most likely to develop T2D.
2型糖尿病（T2D）很常见且患病率不断上升。通过生活方式干预计划可以预防或延缓T2D。这些计划的纳入通常由“中间”范围内的血糖测量值决定。本文研究了糖化血红蛋白（HbA1c）与未来糖尿病风险之间的关系，并确定了不同阈值对识别T2D高危人群的影响。
我们研究了招募至英格兰西南部埃克塞特10000人群队列中的4227名年龄≥40岁的无糖尿病参与者。在研究招募时测量HbA1c，并将重复测量的HbA1c作为常规护理的一部分。根据基线HbA1c，通过灵活的参数生存模型评估5年内发生糖尿病的绝对风险，定义为HbA1c≥48 mmol/mol（6.5%）。
该队列中发生T2D的总体5年绝对风险（95%CI）为4.2%（3.6，4.8%）。在根据HbA1c≥39 mmol/mol（5.7%；美国糖尿病协会标准）分类为“高危”的56%（n = 2358/4224）参与者中，这一风险升至7.1%（6.1，8.2%）。根据国际内分泌学会（IEC）标准，HbA1c≥42 mmol/mol（6.0%），该队列中22%（n = 929/4277）被分类为高危，5年风险为14.9%（12.6，17.2%）。HbA1c值最高（44 - 47 mmol/mol [6.2 - 6.4%]）的人群5年风险更高，为26.4%（22.0，30.5%），而39 - 41 mmol/mol（5.7 - 5.9%）的人群为2.1%（1.5，2.6%），42 - 43 mmol/mol（6.0 - 6.1%）的人群为7.0%（5.4，8.6%）。将预防计划的纳入标准从39 mmol/mol提高到42 mmol/mol（5.7 - 6.0%），高危分类人群比例降低了61%，阳性预测值（PPV）从5.8%提高到12.4%，而对阴性预测值（NPV）的影响可忽略不计，从99.6%降至99.1%。进一步将阈值提高到44 mmol/mol（6.2%），高危分类人群减少了59%，PPV显著从12.4%提高到23.2%，对NPV影响不大（从99.1%降至98.5%）。
使用当前阈值可识别出很大一部分高危人群。提高风险阈值显著减少了被分类为高危并进入预防计划的人数，尽管这必须与漏诊病例相权衡。提高纳入阈值将使有限的干预机会集中在最有可能发生T2D的人群身上。
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