Increasing glucose concentrations and prevalence of diabetes mellitus in northern Sweden, 1990-2007

Background: The prevalence of diabetes in the world is projected to rise from 2.8% in the year 2000 to 4.4% in 2030, an increase suggesting an ongoing global epidemic of diabetes. Objective: To examine time trends in fasting and 2-h glucose concentrations, prevalence and 10-year cumulative incidence of diabetes, and the role of education in these trends. Design: Each year the Vasterbotten Intervention Programme invites all 40, 50, and 60-year-old individuals to a health survey, which includes a cardiovascular risk factor screening and oral glucose tolerance test. The cross-sectional part of the study is based on health examinations conducted between 1990 and 2007 (n = 102,822). The prospective subset (panel dataset) of the study is based on individuals who have had two health examinations 10 years apart and were not defined as having diabetes at their first health examination (n = 23,546). Results: Between 1990 and 2007, the mean population fasting glucose concentration increased 0.5 mmol/L. Comparing the prevalence in 1990-1995 with 2002-2007 demonstrated a significant 44% increase in men (p < 0.001) and a significant 17% increase in women (p < 0.001). Socioeconomic status, here represented by education, clearly influenced both prevalence and incidence of diabetes and glucose concentration. In all time periods and in all age groups, individuals with low education were more likely to have or get diabetes. The 10-year risk of developing diabetes was four to five times higher in the oldest age group (50-60 years) compared with the youngest (30-40 years). A 30% reduction in the 10-year risk of developing diabetes was found in women (p < 0.001) between 2000-2003 and 2004-2007. Conclusions: Despite a clear increase in glucose concentrations and diabetes prevalence between 1990 and 2007, especially in men, there was a decline in the 10-year risk of developing diabetes in women between 2000-2003 and 2004-2007.