9 The evidence

9 The evidence

This section lists the evidence statements from 1 review provided by external contractors and 2 expert reports. The evidence statements are short summaries of the evidence in the review (see What evidence is the guidance based on?). (See Summary of the methods used to develop this guidance for the key to quality assessments.)

The evidence statements are short summaries of evidence, in a review, report or paper (provided by an expert in the topic area). Each statement has a short code indicating which document the evidence has come from. The letter(s) in the code refer to the type of document the statement is from, and the numbers refer to the document number, and the number of the evidence statement in the document.

Evidence statement number 4.1a indicates that the statement is numbered 4.1a in the review. Evidence statement number ER1 indicates that the statement is from expert report 1; evidence statement number ER2 indicates that the statement is from expert report 2 and evidence statement number ER3 indicates that the statement is derived from both expert reports.

The review and expert reports are available at the NICE website.

Evidence statements

Please note that the wording of some evidence statements has been altered slightly from those in the evidence review to make them more consistent with each other and NICE's standard house style.

Evidence statement 4.1a BMI cut-off points indicating 'risk equivalence' for black populations (type 2 diabetes) from UK or western countries

Strong evidence was found from 3 cohort studies (2 [+] and 1 [++]) in Canada and the US1–3 and 3 cross-sectional studies (2 [+] and 1 [++]) in the US4–6 that for a body mass index (BMI) of around 30 kg/m2 in white populations, the equivalent diabetes risk in black populations is at BMI values 0.1–4 units lower (26–29.9 kg/m2). For a BMI of 25 kg/m2 in white populations, the equivalent diabetes risk in black populations was found at BMI values 2–4 units lower (21–23 kg/m2).

These studies had moderate applicability to the UK.

1 Chiu 2011

2 Stevens 2008

3 Stevens 2002

4 Stommel 2010

5 Taylor 2010

6 Pan 2004

Evidence statement 4.2 BMI cut-off points indicating 'risk equivalence' for black populations (myocardial infarction, stroke or mortality) from UK or western countries

Limited evidence was found from 1 (++) cohort study1 that, at a BMI of 20 kg/m2, black populations have an equivalent mortality risk to that seen in white populations at 30 kg/m2. This study has moderate applicability to the UK.

No evidence was found relevant to risk-equivalent BMI cut-points for myocardial infarction or stroke in black populations.

1 Stevens 2002

Evidence statement 4.5a BMI cut-off points indicating 'risk equivalence' for South Asian populations (type 2 diabetes) from UK or western countries

Limited evidence was found from 1 (+) cohort study in Canada1 that, for a BMI of 30 kg/m2 in white populations, the equivalent incident diabetes risk in South Asian populations was found at BMI values 6 units lower (24 kg/m2). No equivalent value to a BMI of 25 kg/m2 was reported.

This study had moderate applicability to the UK.

1 Chiu 2011

Evidence statement 4.5b BMI cut-off points indicating 'risk equivalence' for South Asian populations (type 2 diabetes) from other countries

Limited graphical evidence was found from 1 (+) review1 related to diabetes risk across BMI values, indicating a risk equivalence at 19–20 kg/m2 among South Asian men and 30 kg/m2 among European men. No risk equivalence points were identified for women at this BMI cut-off point, and no values were identified for either men or women equivalent to the risk seen among white Europeans at 25 kg/m2.

This study had moderate applicability to the UK.

1 Nyamdorj 2010b

Evidence statement 4.13a BMI cut-off points indicating 'risk equivalence' for Chinese populations (type 2 diabetes) from UK or western countries

Limited evidence was found from 2 (+) cohorts1,2 that, for a BMI of around 30 kg/m2 in white populations, the equivalent incident diabetes risk in Chinese populations was found at BMI values 2.5–5 units lower. In 1 study2, for a BMI of around 25 kg/m2 in white populations, the equivalent incident diabetes risk in Chinese populations was found at BMI values 2 units lower.

These studies have moderate applicability to the UK.

1 Chiu 2011

2 Stevens 2008

Evidence statement 4.13b BMI cut-off points indicating 'risk equivalence' for Chinese populations (type 2 diabetes) from other countries

One (+) review of studies1 provides limited evidence that, for a BMI of around 30 kg/m2 in white populations, the equivalent incident diabetes risk in Chinese men occurs at BMI values 5 kg/m2 lower for Chinese men and 8 kg/m2 lower for Chinese women.

This review had moderate applicability to the UK.

1 Nyamdorj 2010b

Evidence statement ER 1 BMI cut-off points indicating 'risk equivalence' for South Asian (type 2 diabetes) from the UK

Evidence was found from 1 cross-sectional study in the UK1 that for a BMI of 30 kg/m2 in white populations, the equivalent diabetes risk in South Asian populations is at BMI values 7 units lower (23 kg/m2).

This study had high applicability to the UK.

1 Morris et al. 2013

Evidence statement ER 2 BMI cut-off points indicating 'risk equivalence' for South Asian populations (type 2 diabetes) from the UK

Evidence was found from 1 prospective cohort study in the UK1 that for a BMI of 30 kg/m2 in white populations, the equivalent diabetes risk in South Asian populations is at BMI values 4 units lower (26 kg/m2). For a BMI of 25 kg/m2 in white populations, the equivalent diabetes risk in South Asian populations was found at BMI values 3–4 units lower (21–22 kg/m2).

This study had high applicability to the UK.

1 Tillin et al. 2013

Evidence statement ER 3 BMI cut-off points indicating 'risk equivalence' for black populations (type 2 diabetes) from the UK

Evidence was found from 1 cross-sectional study in the UK1 and 1 prospective cohort study in the UK2 that for a BMI of 30 kg/m2 in white populations, the equivalent diabetes risk in black populations is at BMI values 3 units lower (27 kg/m2). For a BMI of 25 kg/m2 in white populations, the equivalent diabetes risk in black populations was found at BMI values 2–4 units lower (21–23 kg/m2).

These studies have high applicability to the UK.

1 Morris et al. 2013

2 Tillin et al. 2013

  • National Institute for Health and Care Excellence (NICE)