The incidence of type 2 diabetes in the United Kingdom from1991 to 2010

Aims: To characterize the incidence of type 2 diabetes in the UK over the previous 20 years; and determine if there has been an increase in people aged 40 years or less at diagnosis. Methods: For this retrospective cohort study, patients newly diagnosed with type 2 diabetes between 1991 and 2010 were identified from the UK Clinical Practice Research Datalink (CPRD). Patient data were grouped into 5-year intervals by year of diagnosis and age at diagnosis. A standardized incidence ratio (SIR) was determined (1991-1995=100). The percentage of newly diagnosed patients for each age group and aged <= 40 years was calculated for each 5-year calendar period. The incidence rate by age and 5-year calendar period was also determined. Results: In 2010, the crude incidence rate of type 2 diabetes was 515 per 100,000 population. The overall SIR increased to 158 (95% CI 157-160, p<0.001), 237 (235-238, p<0.001) and 275 (273-276, p<0.001) for 1996-2000, 2001-2005 and 2006-2010, respectively. For those <= 40, the respective values were 217 (209-226, p<0.001), 327 (320-335, p<0.001) and 598 (589-608, p<0.001). An increase in incidence occurred with increasing 5-year calendar period. The incidence of type 2 diabetes was higher for males after the age of 40 and higher for females aged <= 40. The percentage of patients aged <= 40 years at diagnosis increased with each increasing 5-year calendar period (5.9, 8.4, 8.5 and 12.4%, respectively). Conclusions: There was a significant increase in the incidence of diagnosed type 2 diabetes between 1991 and 2010 and the proportion of people diagnosed at a relatively early age has increased markedly.