European Journal of Clinical Investigation Vol 38 126 DOI: 10.1111/j.1365-2362.2007.01910.x Blackwell Publishing Ltd ORIGINAL ARTICLES Incidence of type 2 diabetes in Spain Incidence of type 2 diabetes in Spain F. Soriguer et al. ORIGINAL ARTICLE Incidence of type 2 diabetes in southern Spain (Pizarra Study) F. Soriguer * , G. Rojo-Martínez * , M. C. Almaraz * , I. Esteva † , M. S. Ruiz de Adana * , S. Morcillo * , S. Valdés * , E. García-Fuentes † , E. García-Escobar * , I. Cardona * , J. M. Gomez-Zumaquero * and G. Olveira-Fuster * * Hospital Universitario Carlos Haya (REDIMET RD06/0015/0008), Malaga, Spain, † Hospital Universitario Carlos Haya (CIBER de Fisiopatología de la Obesidad y Nutrición (CB06/03) Instituto de Salud Carlos III), Malaga, Spain ABSTRACT Background Few European studies have used an oral glucose tolerance test (OGTT) to examine the incidence of type 2 diabetes. We determined the incidence of impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and type 2 diabetes in a population from southern Spain. Material and methods A population-based cohort study was undertaken in Pizarra, Spain. Baseline data were recorded on age, sex, weight, height, waist and hip circumferences, and diabetes status for 1051 persons, of whom 910 were free of type 2 diabetes (at-risk sample). Of these, 714 completed the 6-year follow-up study. Body mass index, waist-to-hip ratio and weight increase since baseline were calculated. The homeostasis model assessment equations were used to estimate the indices of insulin resistance and β-cell function. Each person received an OGTT at baseline and after 6 years. Results Type 2 diabetes developed in 81 people for a total of 4253 person-years, representing an incidence of 19·1 cases per 1000 person-years (95% confidence interval, 15·3–23·6). Age and the presence of obesity, central obesity and carbohydrate metabolism disorders [IFG (cut off = 100 mg dL –1 , capillary blood glucose level), IGT or both] at baseline were significant markers for the onset of type 2 diabetes during follow-up. After adjusting for these variables, multivariate analysis showed weight increase, waist-to-hip ratio and the indices of insulin resistance and β-cell function were significantly associated with the risk for type 2 diabetes. Conclusions The incidence of type 2 diabetes in a population from southern Spain is high. It is probably associated with the high prevalence of obesity and weight increase in this population. Keywords Cohort population-based study, impaired fasting glucose, impaired glucose tolerance, incidence rate, relative risk, type 2 diabetes. Eur J Clin Invest 2008; 38 (2): 126–133 Introduction The prevalence of type 2 diabetes mellitus varies widely in different parts of the world [1]. The World Health Organization (WHO) has predicted that the prevalence of type 2 diabetes mellitus in people 20 years of age or over will increase five fold by 2025 [2]. The prevalence of type 2 diabetes mellitus in Europe is moderate or low compared with other parts of the world [3]. In Spain, numerous studies have evaluated the prevalence of type 2 diabetes mellitus [4–10], which ranges from 5·6% [5] to 15·9% [10], though it appears to be increasing over the years [4]. Type 2 diabetes mellitus is a potentially preventable disease [11], and studies of the incidence of the disease have led to examination of those variables associated with a greater risk for developing type 2 diabetes. Various prospective studies have been carried out in populations with a high prevalence of diabetes or in subgroups with a greater risk, such as people with impaired glucose tolerance (IGT) [12,13]. Variables associated with the risk for type 2 diabetes include fasting blood glucose levels and post oral glucose tolerance test (OGTT) glucose level [12,13], obesity [14], the pattern of insulin sensitivity [15] or variables associated with lifestyle and physical exercise [16]. However, population-based studies of the incidence of type 2 diabetes, and the conversion to type 2 diabetes of people with a normal OGTT, or with impaired fasting glucose (IFG) or IGT, are less frequent. Two prospective, population-based studies have been undertaken, both in northern Spain [17,18]; the incidence of type 2 diabetes was 8 and 10·8 cases/1000 person/years, respectively.