BackgroundWe investigated if the concentration and “rangeability” of cystatin C (CysC) influenced the prognosis of coronavirus disease 2019 (COVID-19) in patients suffering from, or not suffering from, type 2 diabetes mellitus (T2DM).MethodsA total of 675 T2DM patients and 572 non-T2DM patients were divided into “low” and “high” CysC groups and low and high CysC-rangeability groups according to serum CysC level and range of change of CysC level, respectively. Demographic characteristics, clinical data, and laboratory results of the four groups were analyzed.ResultsCOVID-19 patients with a high level and rangeability of CysC had more organ damage and a higher risk of death compared with those with a low level or low rangeability of CysC. Patients with a higher level and rangeability of CysC had more blood lymphocytes and higher levels of C-reactive protein, alanine aminotransferase, and aspartate aminotransferase. After adjustment for possible confounders, multivariate analysis revealed that CysC >0.93 mg/dL was significantly associated with the risk of heart failure (OR = 2.231, 95% CI: 1.125–5.312) and all-cause death (2.694, 1.161–6.252). CysC rangeability >0 was significantly associated with all-cause death (OR = 4.217, 95% CI: 1.953–9.106). These associations were stronger in patients suffering from T2DM than in those not suffering from T2DM.ConclusionsThe level and rangeability of CysC may influence the prognosis of COVID-19. Special care and appropriate intervention should be undertaken in COVID-19 patients with an increased CysC level during hospitalization and follow-up, especially for those with T2DM.

Background: Since December of 2019, novel coronavirus (SARS-CoV-2)-induced pneumonia (COVID-19) exploded in Wuhan, and rapidly spread throughout China. Patients with COVID-19 demonstrated quite different appearances and outcomes in clinical manifestations. We aimed to figure out whether risk factors of the cystatin C (CysC) and the CysC rangeability are influencing the prognosis of COVID-19 patients with or without type 2 diabetes mellitus (T2DM).Methods: 675 T2DM patients and 602 non-T2DM patients were divided into low CysC group, high CysC group and low CysC rangeability group, high CysC rangeability group according to the serum CysC level and the change range of CysC. Demographic characteristics, clinical data and laboratory results of the four groups were collected and analyzed.Results: Our data showed that COVID-19 patients with high CysC level and CysC rangeability had more organic damage and higher mortality rate compared to those with low level or low rangeability of CysC. Furthermore, patients with higher CysC level and CysC rangeability also demonstrated higher blood lymphocytes (lymph), C-reactive protein (CRP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) which may greatly influence disease progression and poor prognosis of COVID-19. After adjusting for possible confounders, multivariate analysis revealed that CysC≤0.93mg/dl as a reference, CysC＞0.93mg/dl were significantly associated with the risk of heart failure (OR=2.401, 95% CI: 1.118–5.156) and all-cause death (OR=2.734, 95% CI: 1.098-6.811); referring to CysC rangeability≤0, CysC rangeability＞0 significantly associated with all-cause death (OR=4.029, 95% CI: 1.864-8.706). Further grouped by T2DM, these associations were stronger in T2DM than in non-T2DM.Conclusions: It suggests that CysC level and CysC rangeability contribute to clinical manifestations and may influence the prognosis of COVID-19. The CysC is considered as a potential risk factor of the prognosis of COVID-19. Special medical care and appropriate intervention should be performed in COVID-19 patients with elevated CysC during hospitalization and later clinical follow-up, especially for those with T2DM.