Compared with non-diabetic COVID-19 patients, COVID-19 patients with diabetes had significantly higher infectious and inflammatory indicators (all p < 0.05), with procalcitonin increased by 0.077 ng/ml, CRP increased by 26.3 mg/L, WBC increased by 2.23 × 109/L, and neutrophils increased by 2.15 × 109/L. Here, CRP is linked to COVID-19.