OBJECTIVE -To develop and validate an empirical equation to screen for diabetes.RESEARCH DESIGN AND METHODS -A predictive equation was developed using multiple logistic regression analysis and data collected from 1,032 Egyptian subjects with no history of diabetes. The equation incorporated age, sex, BMI, postprandial time (self-reported number of hours since last food or drink other than water), and random capillary plasma glucose as independent covariates for prediction of undiagnosed diabetes. These covariates were based on a fasting plasma glucose level Ն126 mg/dl and/or a plasma glucose level 2 h after a 75-g oral glucose load Ն200 mg/dl. The equation was validated using data collected from an independent sample of 1,065 American subjects. Its performance was also compared with that of recommended and proposed static plasma glucose cut points for diabetes screening.RESULTS -The predictive equation was calculated with the following logistic regression parameters: P ϭ 1/(1 Ϫ e Ϫx ), where x ϭ Ϫ10.0382 ϩ [0.0331 (age in years) ϩ 0.0308 (random plasma glucose in mg/dl) ϩ 0.2500 (postprandial time assessed as 0 to Ն8 h) ϩ 0.5620 (if female) ϩ 0.0346 (BMI)]. The cut point for the prediction of previously undiagnosed diabetes was defined as a probability value Ն0.20. The equation's sensitivity was 65%, specificity 96%, and positive predictive value (PPV) 67%. When applied to a new sample, the equation's sensitivity was 62%, specificity 96%, and PPV 63%.CONCLUSIONS -This multivariate logistic equation improves on currently recommended methods of screening for undiagnosed diabetes and can be easily implemented in a inexpensive handheld programmable calculator to predict previously undiagnosed diabetes.
Diabetes Care 25:1999 -2003, 2002S creening for undiagnosed diabetes is controversial. In 1978, the American Diabetes Association (ADA), the Centers for Disease Control and Prevention, and the National Institutes of Health recommended against screening for diabetes in nonpregnant adults (1). In 1989 and again in 1996, the U.S. Preventive Services Task Force recommended against screening for diabetes in nonpregnant adults (1,2), and in 2001, the ADA recommended against community screening for diabetes (3). Several recent studies have shown that age, sex, BMI, and current metabolic status affect blood glucose levels and have raised concerns about the performance of diabetes screening tests (4 -8).The performance of all screening tests is dependent on the threshold or cut point used to define a positive test. In diabetes screening, choosing a higher glucose cut point reduces sensitivity (probability of a positive screening test given disease) but improves specificity (probability of a negative screening test given absence of disease). Choosing a lower glucose cut point improves sensitivity but reduces specificity. Because the optimal cut point for a positive test may depend on age, sex, BMI, and the time since last food or drink, we propose an alternative approach to interpreting capillary glucose screening tests by deve...