A REASSESSMENT OF FASTING PLASMA-GLUCOSE CONCENTRATIONS IN POPULATIONSCREENING FOR DIABETES-MELLITUS IN A COMMUNITY OF NORTHERN EUROPEAN ANCESTRY - THE WADENA CITY HEALTH STUDY

In current clinical and research practice, the determination of diabet ic status depends largely on plasma glucose levels 2 h after the inges tion of a standard 75-g glucose load, the oral glucose tolerance test (OGTT). The OGTT, however, remains inconvenient, not highly reproducib le, and costly, especially for large-scale studies and population scre ening tests. Fasting plasma glucose (FPG) determinations are convenien t, reliable, and valid measures of glucose intolerance, but the curren tly prescribed cut-off point of 140 mg/dl (7.8 mM) lacks sensitivity. We evaluated the reliability and validity of fasting plasma glucose (F PG) values compared with other measures of hyperglycemia for a diagnos is of diabetes in a population-based study of carbohydrate metabolism in Wadena, Minnesota, a community of predominantly northern European a ncestry. As a part of this effort, a random sample of Wadena adults, s tratified by age and gender, plus all known, previously diagnosed diab etics participated in 2 days of baseline testing and were followed pro spectively and retested 5 years later. Cross-sectional analyses of bas eline data are presented in this article. Diabetic status was ascertai ned by administering a standard OGTT according to National Diabetes Da ta Group (NDDG) specifications. Sensitivity and specificity levels obt ained when using a FPG cut-off point of 6.4 mM were 95.2% and 97.4%, r espectively. In study subjects with no known diagnosis of diabetes, th e FPG cut-off point of 6.4 mM performed reasonably well with a sensiti vity and specificity of 67.7% and 97.4%, respectively. A receiver oper ating characteristic (ROC) curve analysis showed that FPG consistently performed better than glycosylated hemoglobin in distinguishing diabe tic from non-diabetic subjects. FPG concentrations accurately and reli ably discriminate diabetic from non-diabetic individuals in a populati on-based study of Caucasians of northern European ancestry.