1. The Scottish Health Survey: Detecting undiagnosed diabetes and pre-diabetes Catherine Bromley, ScotCen; Sarah Wild, University of Edinburgh; Helen Colhoun, University of Dundee Faculty of Public Health Conference Aviemore 10 November 2011

2. Research questions What is the prevalence of undiagnosed diabetes in adults in Scotland? What is the prevalence of people at increased risk of diabetes (pre-diabetes)? Can risk factors be used to target screening in primary care?

3. Data and definitions Data source 2008, 2009 and 2010 Scottish Health Survey Cross-sectional general population survey conducted in people’s homes Face to face interview followed by a nurse visit (16+) Measurements: BMI, waist circumference, blood pressure, venous blood samples Response to main interview each year: 54%, 56%, 55% Response to blood sample each year: 25% 16-24 yr olds under-represented; men 55+, women 55-74 over- represented Weighting used to adjust sample profile to match household population and to correct for non-response bias

4. Data and definitions Definitions Blood samples were tested for glycated haemoglobin (HbA1c) [analysers calibrated using DCCT standards] HbA1c captures average blood glucose concentration in preceding 3 months Pre-diabetes: HbA1c level >6% - <6.5% Undiagnosed diabetes: HbA1c level >6.5% Thresholds set by an International Expert Committee 2009 2,341 people aged 16+ years provided blood samples and did not have doctor-diagnosed diabetes (self-reported) Of whom, 1,727 were aged 40+ years

5. Risk factors explored here Age 40 years and over; 50 years and over BMI Overweight (BMI 25kg/m 2 - <30kg/m 2 ); obese (30kg/m 2 +) Waist circumference 100 -<110cm, 110cm+ Blood pressure Taking medicine for high BP or told by a doctor that BP is high Diabetes UK risk score Moderate risk; high risk

6. Diabetes UK risk score Derivation (points allocated per risk factor) Age – 49 years and under (0), 50-59 (5), 60-69 (9), 70+ (13) Sex – male (1), female (0) Ethnicity – white European (0), any other group (6) BMI – under 25kg/m 2 (0), 25 -<30 (3), 30 -<35 (5), 35+ (8) Waist circumference – under 90cm (0), 90 -<100cm (4), 100 - <110cm (6), 110cm+ (9) Hypertension – taking medicine for high BP or told by a doctor that BP is high (5) Family history – father/mother/sibling with DI or DM (5) Score range 0-47: 0-6=low risk, 7-15=increased risk, 16- 24=moderate risk, 25+=high risk

7. Diabetes UK risk score – SHeS data Derivation (points allocated per risk factor) Age – 49 years and under (0), 50-59 (5), 60-69 (9), 70+ (13) Sex – male (1), female (0) Ethnicity – white European (0), any other group (6) BMI – under 25kg/m 2 (0), 25 -<30 (3), 30 -<35 (5), 35+ (8) Waist circumference – under 90cm (0), 90 -<100cm (4), 100 - <110cm (6), 110cm+ (9) Hypertension – taking medicine for high BP or told by a doctor that BP is high (5) Family history – father/mother/sibling with DI or DM (5) Score range 0-42: 0-6=low risk, 7-15=increased risk, 16- 24=moderate risk, 25+=high risk

8. Diabetes prevalence

10. Risk factors: age

11. Risk factors: BMI & age 40+

12. Risk factors: Waist circumf. & age 40+

13. Risk factors: Hypertension & age 40+

14. Risk factors: DUK risk tool & age 40+

15. Population burden & yield

20. Screening yield potential

21. Key points Effective risk combinations age 40+ & BMI 25+: but applies to 44% of adults Age 40+ & BMI 30+: useful for undiagnosed diabetes, but only captures half as much pre-diabetes as 40+ & BMI 25+ 40+ & hypertensive: might be worth considering? Diabetes UK moderate or high risk score: useful for both measures, applies to 27% of adults - but requires time to do risk assessment Strengths: Large non-diabetic sample; objective measures Weaknesses: Non-response bias; missing data; small sample for undiagnosed diabetes analysis (n~50)