單靠篩檢與治療無法預防第二型糖尿病


  【24drs.com】根據線上發表於1月4日BMJ期刊的一篇統合分析,不太可能單靠預防第二型糖尿病的兩種策略之一-「篩檢與治療」即有很大的影響。
  
  這個由英國國家糖尿病預防計劃和在美國及澳洲之計劃推動的方法,可辨識那些糖尿病風險高的人,並導致以metformin治療或生活型態介入。
  
  這種替代策略是一種以人群為基礎的方法,每個人都是公共衛生政策(如改變交通方式與使用綠色空間)的目標。
  
  英國牛津大學Nuffield初級照護健康科學系Eleanor Barry等人分析了46篇篩檢檢測研究與50項介入試驗。
  
  他們進行了兩篇統合分析 — 一篇分析是針對已確定糖尿病前期者之篩檢測試的準確性(與口服葡萄糖耐受測試比較),另一篇是評估進行生活介入或使用metformin之後發生糖尿病的相對風險。
  
  他們發現,不論某人是否會發展為第二型糖尿病,篩檢(測量HbA1c值與空腹血漿葡萄糖值)是不佳的預測因子,可能導致錯誤的信心或不必要的治療。
  HbA1c值對於預測高風險(敏感度為49%)或低風險糖尿病者(專一度為79%)都是無效。
  
  空腹血漿葡萄糖值的平均敏感度為25%、專一度為94%。
  
  進行3-6年的生活型態介入顯示,從第6個月到6年時,第二型糖尿病的相對風險降低36%,在追蹤研究期間降低到20%。但是,作者們承認他們對這些估計只有中度到非常低的信心,因為研究品質通常偏低。
  
  使用metformin的患者在服用該藥期間,其相對風險降低26%。
  
  此外,分析發現,國際上對於什麼是前期糖尿病的定義並不一致。作者們指出,如果研究者使用美國糖尿病協會(ADA)而非世界衛生組織(WHO)的定義,前期糖尿病人數將會加倍。
  
  WHO和國際專家委員會建議,對那些空腹血漿葡萄糖值6.0-6.9 mmol/L與HbA1c值42-47 mmol/mol (6.0–6.4%)的人診斷為前期糖尿病。
  
  相對的,ADA使用的閾值是:空腹血漿葡萄糖值5.6 - 6.9 mmol/L或HbA1c 值39 - 47 mmol/mol (5.7–6.4%)。
  
  Barry醫師等人結論指出,篩選測試是不佳的預測因子,但是,對於有動機且有社會支持維持改變的人,介入方式在減少病程進展為糖尿病方面有一些成功 。
  
  不過,他們承認,這些人數很少,所以他們建議進行更多人口的介入方式研究。
  
  尋找正確的預防策略是很重要的,因為全世界的流行率上升。作者們寫道,有4億2200萬成年人患有糖尿病,而在2005-2030年間,預期死於其併發症的人數將會倍增。
  
  如果單看英國的資料,已經有320萬人診斷患有第二型糖尿病,到了2025年,此數據預期增加至500萬,將佔英國國家健保局支出達237億英鎊(約302億美元) 。
  
  在編輯評論中,英國Coventry Warwick大學Warwick醫學院公衛醫學暨健康科技評估教授Norman Waugh認為,因為以前的研究發現,在一般人口中進行篩檢是準確和有成本效益的,需要更多研究探討不同的、非空腹的檢測方法。
  
  他表示,鑑於HbA1c與空腹血漿葡萄糖值的缺陷,遺憾的是,沒有針對非空腹50 g葡萄糖挑戰測試的更多研究,它大多是用於篩檢妊娠糖尿病,但是很少用於篩檢第二型糖尿病或葡萄糖耐受不佳。
  
  他建議,在篩檢及治療個人和鼓勵改變生活型態之政策與維持整個人口的這些變化之間取得平衡,不過,他也承認,遵守生活型態建議的比率是很低的。
  
  他表示,政策改變可以包括對一些食物和含糖飲料徵稅,或將自行車車道與交通車車道分開。
  
  Waugh醫師寫道,預防或延遲第二型糖尿病需要有效的措施,以激勵一般民眾保護自己的健康。
  
  資料來源:http://www.24drs.com/
  
  Native link:'Screen and Treat' Alone Unlikely to Prevent Type 2 Diabetes
  

'Screen and Treat' Alone Unlikely to Prevent Type 2 Diabetes

By Marcia Frellick
Medscape Medical News

"Screen and treat," one of two strategies for preventing type 2 diabetes, is unlikely on its own to have much of an impact, according to a meta-analysis published online January 4 in the BMJ.

That approach, promoted by the United Kingdom's National Diabetes Prevention Programme and programs in the United States and Australia, among others, identifies those at high risk for diabetes individually and leads to treatment with metformin or lifestyle intervention.

The alternate strategy is a population-based approach where everyone is targeted through public-health policies, such as changes to transportation and use of green spaces.

Eleanor Barry, MBBS, of the Nuffield Department of Primary Care Health Sciences at University of Oxford in the United Kingdom, and colleagues, analyzed 46 studies of screening tests and 50 intervention trials.

They did two meta-analyses — one to study the accuracy of screening tests (compared with the oral glucose tolerance test) in identifying prediabetes and another to assess relative risk of developing diabetes after lifestyle interventions or metformin.

They found that the screenings (measuring HbA1c levels and fasting plasma glucose) were poor predictors of whether someone would develop type 2 diabetes and could lead to false confidence or unnecessary treatments.

HbA1c was ineffective both at predicting people at high risk (sensitivity levels of 49%) or low risk for diabetes (specificity 79%).

Fasting plasma glucose had a mean sensitivity of 25% and specificity of 94%.

Lifestyle interventions spanning 3 to 6 years showed a 36% drop in relative risk of type 2 diabetes from 6 months to 6 years, which fell to 20% in follow-up studies. But the authors acknowledge: "We have only moderate to very low confidence in these estimates, however, because study quality was often low."

Patients using metformin saw a relative risk reduction of 26% while taking the drug.

In addition, the analysis found inconsistency internationally as to what constitutes prediabetes. The authors note that prediabetes numbers would double if researchers used the American Diabetes Association's (ADA) cutoffs rather than the World Health Organization (WHO) cutoffs.

WHO and the International Expert Committee recommend diagnosis of prediabetes for those with a fasting plasma glucose of 6.0 to 6.9 mmol/L and HbA1c of 42-47 mmol/mol (6.0–6.4%).

By contrast, the ADA uses a cutoff for fasting plasma glucose of 5.6 to 6.9 mmol/L or HbA1c of 39 to 47 mmol/mol (5.7–6.4%).

Dr Barry and colleagues conclude that screening tests are poor predictors, but interventions have some success in reducing progression to diabetes for those who have the drive and the social support to sustain the changes.

However, those numbers will be small, they acknowledge, so they recommend more research into populationwide interventions.

422 Million Adults Living With Diabetes

Finding the right prevention strategy is critical as the prevalence surges worldwide. The authors write that "422 million adults are living with diabetes, and the number expected to die from its complications is predicted to double between 2005 and 2030."

Looking at the United Kingdom alone, already 3.2 million people have been diagnosed with type 2 diabetes. By 2025, that number is expected to grow to 5 million, at a cost of £23.7 billion ($30.2 billion) to the National Health Service.

In an accompanying editorial, Norman Waugh, MBChB, professor of public-health medicine and health-technology assessment at Warwick Medical School, University of Warwick, Coventry, United Kingdom, suggests more studies on a different, nonfasting test, given that previous studies have found it accurate and cost-effective for screening in the general population.

"Given the imperfections of HbA1c and fasting plasma glucose, it is a pity that more research has not been done on the nonfasting 50-g glucose challenge test, much used in screening for gestational diabetes but rarely used in screening for type 2 diabetes or impaired glucose tolerance," he says.

He suggests a balance of screening and treating individuals and policies that encourage changing lifestyle and maintaining that change across whole populations, although he acknowledges adherence to lifestyle advice is low.

Policy changes can include taxing some foods and sugary drinks or separating bike lanes from traffic lanes, he says.

"Preventing or delaying type 2 diabetes requires effective measures to motivate the general population to protect their own health," Dr Waugh writes.

The study authors and Dr Waugh declare no relevant financial relationships.

    
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