Criteria for previously undiagnosed diabetes and risk of mortality: 15 year follow-up of the Edinburgh Artery Study cohort

Aims To compare risk of all-cause and cardiovascular mortality associated with different criteria for undiagnosed diabetes and glucose tolerance.

Methods A population-based cohort of 758 men and 738 women of 55-74 years of age who had an oral glucose tolerance test or known diabetes at baseline were followed up until death or for 15 years. Mortality outcomes were compared by baseline diabetes status using people with normal glucose tolerance (i.e. those without diabetes, impaired fasting glucose or impaired glucose tolerance) as the reference group.

Results Prevalence of undiagnosed diabetes using World Health Organization (WHO) criteria (fasting glucose of >= 7.0 mmol/l and/or a 2-h post-challenge glucose of >= 11.1 mmol/l) was 6.6%, of which 81% was associated with fasting glucose >= 7.0 mmol/l and 19% was associated with isolated post-challenge hyperglycaemia. Hazard ratios (95% CI) for all-cause mortality adjusted for age and sex were 1.51 (1.09-2.08) for new diabetes by the American Diabetes Association (ADA) criterion (fasting glucose of >= 7.0 mmol/l regardless of post-challenge glucose), 1.60 (1.20-2.13) for new diabetes by WHO criteria and 1.98 (1.14-3.44) for isolated post-challenge hyperglycaemia. Hazard ratios (95% CI) for cardiovascular mortality adjusted for age and sex were 1.89 (1.17-3.00), 1.73 (1.12-2.66) and 1.08 (0.34-3.40) for new diabetes by ADA and WHO criteria and for isolated post-challenge hyperglycaemia, respectively.

Conclusions Undiagnosed diabetes was associated with increased risk of all-cause mortality by any criteria but significantly increased cardiovascular disease mortality was only associated with diabetes diagnosed using the fasting glucose criterion. Mortality risks were similar in this population using either ADA or WHO criteria for diagnosis of diabetes.