Background: The prevalence of Type 2 diabetes is increasing worldwide; predictions suggest that the disease will reach epidemic proportions this century. This study aims to estimate the extent of the increase in prevalence of diagnosed Type 2 diabetes in British men between 1978 and 2005.
Methods: A representative cohort of 7722 British men aged 40-59 years at entry in 1978-1980 were selected from general practices in 24 British towns. Seven sequential questionnaire surveys were carried out between 1978 and 2005, recording recall of a doctor diagnosis of diabetes at each time point. Logistic regression models with generalized estimating equations were fitted to provide age-adjusted estimates of the calendar year increases in odds of Type 2 diabetes, both overall and for consecutive periods, each of approximately 5 years.
Results: The crude prevalence of Type 2 diabetes increased from 1.2% in 1978-1980 to 12.1% in 2005. The age-adjusted average annual increase in Type 2 diabetes prevalence for the 27-year study period was 7.0% [95% confidence interval (CI) 5.4%, 8.6%]. However, the age-adjusted annual rate of increase increased over time, from 4.3% (95% CI 0.4%, 8.2%) between 1979 and 1984 to 11.8% (95% CI 8.4%, 15.4%) between 2003 and 2005; P (trend) = 0.01. The highest annual increases occurred in subjects with higher mean body mass index levels and in towns in Scotland.
Conclusions: The prevalence of Type 2 diabetes has risen substantially in Britain during the last three decades; the recent rate of increase has been almost three times greater than that in the early 1980s.