Vitamin D levels associate with blood glucose and BMI in COVID-19 patients predicting disease severity.

Context High prevalence of Vitamin-D (VD) deficiency in COVID-19 patients was reported and hypothesized to increase COVID-19 severity likely due to its negative impact on immune and inflammatory responses. Furthermore, clear associations between hypovitaminosis-D and fat body-mass excess and diabetes, factors associated with COVID-19 severity, have been widely recognized. Objective The aim of this study was to evaluate in COVID-19 patients the relationship between VD levels and inflammatory response, BMI, blood glucose and disease severity. Design Patients admitted to San Raffaele-Hospital for COVID-19 were enrolled in this study, excluding those with comorbidities and therapies influencing VD-metabolism. 25(OH)VD levels, plasma glucose levels, BMI and inflammatory parameters were evaluated at admission. Results A total of 88 patients were included. Median VD level was 16.3 ng/mL and VD-deficiency was found in 68.2% of patients. VD-deficiency was found more frequently in male patients and in those affected by severe COVID-19. Regression analyses showed a positive correlation between VD and PaO2/FiO2 ratio, and negative correlations between VD and plasma glucose, BMI, Neutrophil/Lymphocyte ratio, CRP and IL-6.Patients with both hypovitaminosis-D and diabetes mellitus, as well those with hypovitaminosis-D and overweight, were more frequently affected by a severe disease with worse inflammatory response and respiratory parameters, compared to those without or just one of these conditions. Conclusions We showed, for the first-time, a strict association of VD levels with blood glucose and BMI in COVID-19 patients. VD-deficiency might be a novel common pathophysiological mechanism involved in the detrimental effect of hyperglycemia and adiposity on disease severity.