Modified Bland-Altman analysis comparing the difference (glucose value obtained by each method–reference value) with the reference value. The bias is the mean relative difference as a percentage of the reference value. A bias of 5% means that the value is on average 5% higher than the reference value. aMean absolute relative difference as a percentage of the reference value. bStandard deviation of the bias. cLower 95% limits of agreement define bias −1.96 CV. dUpper 95% limits of agreement define bias +1.96 CV. CL: central laboratory; CV: coefficient of variation; HC201+: HemoCue 201+; HC201RT: HemoCue 201 RT; MARD: mean absolute relative difference.