Use of the diabetes risk score for opportunistic screening of undiagnosed diabetes and impaired glucose tolerance: the IGLOO (Impaired Glucose Tolerance and Long-Term Outcomes Observational) study.

Objective: To evaluate an opportunistic screening strategy addressed to individuals with one or more cardiovascular risk factor, based on the Diabetes Risk Score (DRS) as the initial instrument, for the identification of individuals with type 2 diabetes or impaired glucose tolerance (IGT).
Research Design and Methods: The DRS, a simple self-administered questionnaire, was completed by individuals identified by general practitioners and presenting with one or more cardiovascular risk factor. All patients underwent a 2-h oral glucose tolerance test (OGTT). The optimal DRS cutoff was calculated by applying the receiver-operating characteristic curve.
Results: Overall, 1,377 individuals aged between 55 and 75 years received an OGTT and completed the DRS. Mean DRS values showed a marked variation according to glucose metabolism categories, as follows: 8.7 +/- 3.0 in normoglycemic individuals, 9.5 +/- 3.1 in individuals with impaired fasting glucose, 9.9 +/- 3.3 in individuals with IGT, and 12.0 +/- 3.5 in individuals with type 2 diabetes. The receiver-operating characteristic curve showed that, with a cutoff of 9, the sensitivity of DRS in detecting individuals with glucose abnormalities (type 2 diabetes or IGT) was 77% and the specificity 45%. The use of the DRS as an initial screening instrument, followed by the measurement of fasting blood glucose in individuals with a score > or =9 and by the OGTT in individuals with a fasting blood glucose between 5.6 and 6.9 mmol/l, would lead to the identification of 83% of the case subjects with type 2 diabetes and 57% of the case subjects with IGT, at a cost of an OGTT in 38% of the sample and a fasting blood glucose in 64%.
Conclusions: The DRS can represent a valid inexpensive instrument for opportunistic screening and a useful alternative to indiscriminate fasting blood glucose measurement, not readily available in general practice.