Prevalence of diabetes mellitus in the elderly of Namwon County, South Korea

Abstract

Background: Ethnic and geographic differences exist in the prevalence of diabetes mellitus which has increased dramatically in South Korea. A few community-based epidemiologic studies with oral glucose tolerance test were performed in South Korea. The purpose of this study was to determine the prevalence of diabetes mellitus by the World Health Organization (WHO) and the American Diabetic Association (ADA) diagnostic criteria and to investigate their associated risk factors. Also, we compared and analyzed the characteristics of Koreans by WHO and ADA diagnostic criteria.

Methods: Between March 22, 1999 and July 14, 1999, a random sampling of 1,445 residents over 40 years of age in five villages (3 myons and 2 dongs) in Namwon City. Chollabuk-do Province, South Korea was carried out. WHO and ADA diagnostic criteria were used for the prevalence of DM, IGT and IFG. The associated factors of subjects were analyzed.

Results: After age adjustment for the population projection of Korea (1999), the prevalence of DM and IGT was 13.7% and 13.8%, respectively, by WHO criteria, while the prevalence of DM, IGT and IFG was 15.8%, 12.8% and 5.7%, respectively, by ADA criteria, and the previous diagnosed diabetics were 5.8% in 665 adults over 40 years of age in the Namwon area. The age-adjusted prevalence of previously diagnosed diabetics was 5.8%. When the subjects classified by both criteria were compared, the level of agreement between WHO and ADA diagnostic criteria, except IFG, was very high (kappa = 0.94; p < 0.001). The ROC curve analysis determined FSG of 114.5 mg/dL (6.4 mmol/L) to yield optimal sensitivity and specificity corresponding to a PP2SG 200 mg/dL (11.1 mmol/L). The prevalence of DM and IGT with ADA diagnostic criteria rose with increasing age (p < 0.05). The body mass index was mean 23.8 +/- 3.4 in all the subjects, 23.75 +/- 3.46 in NGT group and 23.67 +/- 3.16 in DM group, but the differences in the prevalence of DM, IGT and IFG by BMI were not significant. The prevalence of DM rose significantly with the increase in the waist-hip ratio (p < 0.05). The prevalence of DM significantly increased in subjects by increases in blood pressure, and triglyceride and the relative risk in the prevalence of DM was significantly high with dyslipidemia (Odds ratio 2.29, 95% CI: 1.16-3.49).

Conclusion: The prevalence of Diabetes Mellitus in the population over 40 years of age in Namwon City. South Korea remarkably increased compared with the 1970s and 1980s and was similar to that of the West. Ethnic differences in obesity of normal, DM and IGT subjects and in the effect on the prevalence of DM may exist in the Korean population, but they were not significant. As there is a limit in number, it is considered that a general population-based epidemiologic study on a large scale is required to investigate ethnic and geographic differences for the risk factors of DM in South Korea. The level of agreement, except IFG, by WHO and ADA diagnostic criteria was high, which indicates that these results may show that not only fasting serum glucose but also postprandial 2-h serum glucose are important for diagnosing diabetes in Korean.