Objective: The aim of this study was to define the incidence of type 2 diabetes in a low-risk Caucasian population in northern Spain and its association with various risk factors.
Research design and methods: The Asturias Study is a prospective, population-based survey of diabetes and cardiovascular risk factors. The baseline examination was carried out during 1998-1999 when 1,034 individuals, aged 30-75 years, were randomly selected to determine the prevalence of type 2 diabetes and pre-diabetes in the Principality of Asturias (northern Spain). In 2004-2005, these same subjects were invited for a follow-up examination; 700 participated. This study includes only those individuals who did not have diabetes at baseline. We used the World Health Organization 1999 criteria to classify glucose metabolism at both baseline and follow-up.
Results: The incidence of diabetes adjusted for the age and sex structure of Asturias was 10.8 cases/1,000 person-years (95% CI 8.1-14.8). The incidence rates were 5 cases/1,000 person-years in individuals with normoglycemia, 21 cases/1,000 person-years in individuals with isolated impaired glucose tolerance (IGT), 34.7 cases/1,000 person-years in individuals with isolated impaired fasting glucose (IFG), and 95.2 cases/1,000 person-years in individuals with combined IFG-IGT. Stepwise multiple logistic regression analysis showed that, together with fasting plasma glucose (FPG) and 2-h plasma glucose, which were the strongest predictors of diabetes, triglycerides and BMI were also independently associated with progression to diabetes.
Conclusions: In this 6-year prospective population-based study, we found an incidence of type 2 diabetes of 10.8 cases/1,000 person-years. Both FPG and 2-h plasma glucose were strongly predictive of diabetes, and their effect was additive.