What will be the Proper Criteria for Impaired Fasting Glucose for Korean Men?: Based on Medical Screening Data from a General Hospital

Ryu, Seungho; Chang, Yoo Soo; Kim, Dong Il; Suh, Byung Seong; Kim, Woon Sool

Abstract

OBJECTIVES
Recently, the American Diabetes Association (ADA) redefined the criteria of prediabetes, which has lowered the diagnostic level of fasting plasma glucose (FPG) from 110 to 125 mg/dl, down to levels between 100 to 125mg/dl. The purpose of this study was to determine the predictive cutoff level of FPG as a risk for the development of diabetes mellitus in Korean men. METHODS: A retrospective cohort study was conducted on 11, 423 (64.5%) out of 17, 696 males < or =30 years of age, and who met the FPG of < or =125 mg/dl and hemoglobin A1c of < or = 6.4% criteria, without a history of diabetes, and who were enrolled at the screening center of a certain university hospital between January and December 1999. The subjects were followed from January 1999 to December 2002 (mean follow-up duration; 2.3 (+/-0.7) years). They were classified as normal (FPG < 100mg/dl), high glucose (FPG > or =100mg/dl and < 110mg/dl) and impaired fasting glucose (FPG > or =110mg/dl and < or =125mg/dl) on the basis of their fasting plasma glucose level measured in 1999. We compared the incidence of diabetes between the 3 groups by performing Cox proportional hazards model and used receiver operating characteristic analyses of the FPG level, in order to estimate the optimal cut-off values as predictors of incident diabetes. RESULTS: At the baseline, most of the study subjects were in age in their 30s to 40s (mean age, 41.8 (+/-7.1) year). The incidence of diabetes mellitus in this study was 1.19 per 1, 000 person-years (95% CI=0.68-1.79), which was much lower than the results of a community-based study that was 5.01 per 1, 000 person-years. The relative risks of incident diabetes in the high glucose and impaired fasting glucose groups, compared with the normal glucose group, were 10.3 (95% CI=2.58-41.2) and 95.2 (95% CI= 29.3-309.1), respectively. After adjustment for age, body mass index, and log triglyceride, a FPG greater than 100mg/dl remained significant predictors of incident diabetes. Using the receiver operating characteristic (ROC) curve, the optimal cutoff level of FPG as a predictor of incident diabetes was 97.5 mg/dl, with a sensitivity and a specificity of 81.0% and 86.0%, respectively. CONCLUSION: These results suggest that lowering the criteria of impaired fasting glucose is needed in Korean male adults. Future studies on community-based populations, including women, will be required to determine the optimal cutoff level of FPG as a predictor of incident diabetes.