Screening for diabetes using an oral glucose tolerance test within a western multi-ethnic population identifies modifiable cardiovascular risk: the ADDITION-Leicester study

The aim of this study was to determine the frequency of undiagnosed glucose abnormalities and the burden of cardiovascular disease (CVD) risk among south Asians and white Europeans attending a systematic screening programme for type 2 diabetes (ADDITION-Leicester) and to estimate the achievable risk reduction in individuals identified with glucose disorders. Random samples of individuals (n = 66,320) from 20 general practices were invited for a 75 g OGTT and CVD risk assessment. Ten-year CVD risk among screen-detected people with diabetes or impaired glucose regulation (IGR) (impaired fasting glycaemia and/or impaired glucose tolerance [IGT]) was computed using the Framingham-based ETHRISK engine and achievable risk reduction was predicted using relative reductions for treatments extracted from published trials. A total of 6,041 participants (48% male, 22% south Asian) aged 40-75 years inclusive were included. Undiagnosed glucose disorders occurred more frequently in south Asians than white Europeans; age and sex adjusted odds ratios were 1.74 (95% CI 1.42-2.13) and 2.30 (95% CI 1.68-3.16) for IGT and diabetes respectively. Prevalence of any undetected glucose disorder was 17.5% in the whole cohort. Adjusted 10-year risk was similar in screen-detected people with IGR and diabetes (18.3% vs 21.6%), and was higher in south Asians across the glucose spectrum. Absolute CVD risk reductions of up to 13% in those with screen-detected type 2 diabetes and 6% in IGR are achievable using existing cardioprotective therapies. Population screening with an OGTT identifies a significant burden of modifiable CVD risk, especially within south Asian groups. Strategies enticing this population to consider screening programmes are urgently needed as significant risk reduction is possible once a glucose abnormality is identified. ClinicalTrials.gov NCT00318032 The project is funded for support and treatment costs by NHS Department of Health Support for Science and project grants.