Test agreement for classifying diabetes in indigenous Australians

Objective: To evaluate for Indigenous Australians the agreement between a fasting plasma glucose (FPG) criterion of 7.0 mmol/L and diabetes test results using a two-hour oral glucose tolerance test (OGTT), comparing relationships between test agreement and prevalence to similar studies. Methods: Screening was undertaken in 25 remote settlements. Agreement between FPG and OGTT results was evaluated using the kappa coefficient (chance-corrected agreement). Results: Participants (n=3,249) ranged from 15-94 years. Kappa ranged from 0.70-0.77 for diabetes prevalence of 5-30%, with overall agreement of 0.76. In comparison studies, the relationship between kappa and diabetes prevalence was similar, but with kappa 0.21-0.48. Conclusions and implications: A FPG test with a 7.0 mmol/L cut-off is a reliable screening method, relative to the OGTT, for remote Indigenous settlements. The level of agreement between the FPG test and the OGTT for the Indigenous population surveyed is superior by far to agreement reported for non-Indigenous samples.