In addition, FPG was positively correlated with classification of COVID-19 (r = 0.393, P < 0.001), past DM history (r = 0.498, P < 0.001), SAA (r = 0.432, P < 0.001), CRP (r = 0.378, P < 0.001), ESR (r = 0.440, P < 0.001), and imaging changes of chest CT (r = 0.318, P = 0.001), while negatively correlated with CD8+ T cell number (r = −0.272, P = 0.006) (Table 5). Here, CRP is linked to diabetes mellitus.