<qa>  What is the benefit of a one-step procedure?Significance to DM: This study will evaluate the diagnostic efficacy, cost-effectiveness and clinical outcomes of three methods. A one-step procedure may be better tolerated compared to a two-step approach with respect to number of visits, amount of drink and length of testing. Furthermore, diagnosis by a single test may avoid unnecessary delay in initiation of therapy and still identify those patients at risk for type 2 DM. 