Time trend analysis of the prevalence and incidence of diagnosed type 2 diabetes among adults in Taiwan from 2000 to 2007: a population-based study

Background: The prevalence of type 2 diabetes has rapidly increased in the Taiwanese population with the increasing prevalence of a sedentary lifestyle and high-calorie dietary intake. This study aims to determine the annual trends of the prevalence and incidence of diagnosed type 2 diabetes among adults in Taiwan from 2000 to 2007. Methods: A population-based study of all residents aged 20 years and over (12,191,076 in 2000 and 18,772,180 in 2007) enrolled in the National Health Insurance (NHI) program, the database of which was used to identify patients diagnosed with type 2 diabetes. The annual prevalence and incidence of diagnosed type 2 diabetes were estimated using the International Classification of Diseases, 9th Revision, Clinical Modification diagnostic codes based on age, gender, insurance premium, and urbanization degree. Logistic regression was used to estimate the odds ratios (OR) of risk factors, as well as to examine the trend in the annual prevalence or incidence of diagnosed type 2 diabetes from 2000 to 2007. Results: The crude annual prevalence of diagnosed type 2 diabetes increased significantly from 5.79% in 2000 to 8.30% in 2007. The increase was highest in 2007, among men, individuals aged >= 80 years, and individuals residing in aging society areas [OR (95% CI): 1.416 (1.412-1.420), 1.033 (1.032-1.034), 31.810 (31.690-31.931), and 1.090 (1.085-1.094), respectively]. The crude incidence fluctuated throughout the study period, ranging from 7.72 per 1,000 in 2006 to 8.98 per 1,000 in 2000. The decrease was highest in 2006, among individuals with an insurance premium >= median value [0.933 (0.925-0.942) and 0.810 (0.805-0.815), respectively]. The greatest increase was among men, individuals aged 60 to 79 years, and individuals residing in aging society areas [1.150 (1.145-1.155), 15.452 (15.329-15.576), and 1.127 (1.113-1.142), respectively]. Conclusion: This study demonstrated the substantial increase in annual prevalence of diagnosed type 2 diabetes among adults in Taiwan from 2000 to 2007. The incidence fluctuated between 2000 and 2007.