Table 2.

Cross-validation Results

FPIR by Insulin IEMA	FPIR by Insulin RIA Below-threshold	FPIR by Insulin RIA Above-threshold	Total
Below-threshold	17	0	17
Uncertain	30	21	51
Above-threshold	0	93	93
Total	47	114	161

Each cell shows the number of IVGTTs yielding simultaneous FPIR results by the insulin RIA (the “reference standard”) and the insulin IEMA. Below- and above-threshold FPIRs by the insulin RIA used the established cutpoints of 60 and 100 µU/ml depending on subject’s age and relationship to the proband with type 1 diabetes (see text), which corresponded to the respective cutpoints (95% CI) of 36.76 µU/ml (17.17, 56.35) and 62.93 µU/ml (43.34, 82.53) by the insulin IEMA as interpolated using Model 1 (Table 1). A Below-threshold FPIR by the insulin IEMA meant that the subject’s value was below the lower 95% confidence limits (<17.17 or < 43.34 µU/mL), an Above-threshold FPIR meant that the subject’s value exceeded the upper 95% CI (> 56.35 or > 82.53 µU/ml), and an Uncertain FPIR meant that the subject’s value was within the 95% CI.