Undiagnosed diabetes in the over-60s: performance of the Association of Public Health Observatories (APHO) Diabetes Prevalence Model in a general practice

Abstract

Aim: The Association of Public Health Observatories (APHO) Diabetes Prevalence Model has been interpreted to suggest that a substantial number of people with diabetes are 'missed'. An affluent suburb of Newcastle upon Tyne has a low known diabetes prevalence. We aimed to determine the true prevalence of diabetes in the practice population aged over 60 years and compare our prevalence estimate with that of the Association of Public Health Observatories Diabetes Prevalence Model (18.0%; uncertainty limit 10.7-27.7%). At baseline, the known prevalence of diabetes in this group was 7.4%.

Methods: All individuals aged 60 years and over registered with one general practice in Newcastle-upon-Tyne, not known to have diabetes (n = 1375), were invited for a standard oral glucose tolerance test and measurement of HbA(1c). Standard World Health Organization cut points for fasting and post-challenge glucose on oral glucose tolerance test or HbA(1c) ≥ 48 mmol/mol (6.5%) were used to identify diabetes.

Results: Five hundred and eighty-four individuals (42.5%) attended for screening. Using oral glucose tolerance test criteria, 4.5% were identified with undiagnosed diabetes. Using HbA(1c), 3.1% had undiagnosed diabetes. The estimated prevalence of total diabetes for the practice population aged 60 years and older is 11.8 (10.5-13.2%) and 10.3 (9.3-11.6) for oral glucose tolerance test and HbA(1c) criteria, respectively.

Conclusions: The prevalence of diabetes in those aged 60 years and older registered with this practice is lower than the point estimate of the Association of Public Health Observatories Diabetes Prevalence Model, but within its uncertainty limits. Application of the Association of Public Health Observatories model must take into account its uncertainty limits.