Average relative response (L.H) represents the peak area ratio of light to heavy signal. bThe correlation coefficient for each protein () represents the linearity of the MRM analysis. cRetention time (RT) represents the average retention time in 60 individual samples. dRT CV% represents the retention time variation in the No DR, Mi NPDR, and Mo NPDR groups. eLowest limit of detection (LLOD) is calculated based on the variance of the blank sample and the standard deviation (S.D.) of the sample with the lowest “spiked” in concentration. fThe lowest limit of quantitation (LLOQ) was calculated as follows: LLOQ = LLOD 3. gNormal protein concentrations in plasma were obtained by literature searches as described in the Results section.