We compared the clinical characteristics, treatments, and prognoses of fungal keratitis in patients with and without diabetes. Patients diagnosed with fungal keratitis at Shandong Eye Institute between January 2010 and December 2016 were retrospectively reviewed and classified as diabetic and nondiabetic groups. One-hundred-and-eleven patients (111 eyes) with diabetes and 740 patients (740 eyes) without diabetes were included. The diabetic patients showed significantly older (p< 0.05) and lower male:female ratio (p<0.05). Plants trauma was the primary risk factor in both groups, and there was no significant difference of pathogen type (the most common was Fusarium genus, followed by Alternaria and Aspergillus genera). Multivariate logistic regression analyses revealed that diabetes and topical glucocorticoid use were the independent risk factors for the severity of fungal keratitis. The recurrent infection rate between the diabetic and nondiabetic patients during the follow-up (6 to 24 months) after penetrating keratoplasty (PKP) was not significantly different. Although the recurrent epithelial defect, rejection, and best-corrected visual acuity were similar between the patients with matched bed/graft size (7.75/8.0 mm) in the two groups 1 year after PKP, the incidence of delayed re-epithelialization (>7 days) was significantly higher in diabetic patients (3/10 versus 2/43 in nondiabetic patients, p<0.05). More specially, the diabetic patients with the duration ≥10 years showed more significantly delayed re-epithelialization than those with the diabetic duration less than 10 years (3/5 versus 1/26, p<0.05). In conclusion, the diabetes mellitus is an independent risk factor that affect the severity of fungal keratitis. Corneal re-epithelialization was significantly delayed after PKP in the diabetic patients, especially with the duration ≥10 years.