FGF7 and diabetes mellitus: Among the COVID-19 patients without a history of diabetes, there were no significant differences in the serum FGF7 levels among the uninfected (20.30 ± 8.85 pg/ml), mild (17.20 ± 5.88 pg/ml) and severe (20.27 ± 6.59 pg/ml) patients (Fig. 5b).