The SIGT study sought to develop a low-cost screening test for identifying people with pre-diabetes and diabetes in the general population. The gold standard test to determine glucose tolerance , the oral glucose tolerance test (OGTT), is time-intensive and inconvenient for patients. The study hypothesized that using a simpler test, an oral glucose challenge test (GCT), could constitute an effective and low-cost method of screening for diabetes in adults. The GCT is currently used in screening for gestational diabetes, which is pathophysiologically similar to early glucose intolerance (high glucose levels after a challenge).

Participants without a prior diagnosis of diabetes were enrolled and performed two outpatient visits. At the first visit, participants underwent a GCT, which involved drinking 50 g oral glucose within 5 min and measurement of plasma and capillary glucose after 1 h. At the second visit, participants received an OGTT following an overnight fast, with samples at baseline, 1 and 2 h. Investigators used the test results to compare the performance of the the GCT to the OGTT for determining glucose tolerance, ie prediabetes or diabetes.

The SIGT study sought to develop a low-cost, convenient, and effective screening test for identifying people with pre-diabetes or diabetes in the general population.

Receiver operating characteristic (ROC) curves were generated to assess the effectiveness of the GCT test in identifying prediabetes, and diabetes. GCT performance was also assessed in subgroups with differences in risk factors such as age, BMI, and family history of diabetes. Estimated costs of screening were generated to examine the cost-effectiveness of the various screening tests.

This study enrolled individuals who had no prior diagnosis of diabetes, were not pregnant or nursing, not taking glucocorticoids, and were well enough to have worked during the previous week.

The SIGT study concluded that GCT screening would be an accurate, convenient and relatively inexpensive way to detect prediabetes and previously unrecognized diabetes.