Study Draws Link Between Vitamin D Levels and Blood Glucose, BMI and COVID-19 Severity

A substudy of a prospective observational study performed at a hospital in Italy details potential associations of vitamin D levels with BMI and blood glucose and severity of COVID-19.

A recent study from the San Raffaele Hospital in Italy suggests presence of low vitamin D levels could help predict risk of increased disease severity with COVID-19 in patients with diabetes or obesity.

A retrospective substudy of the COVID-BioB study, results of the analysis detail an associations of vitamin D levels with blood glucose and body mass index (BMI) in patients with severe COVID-19.

“We showed, for the first time, a significant association between VD levels and male sex, blood glucose levels and BMI in COVID-19 and since male sex, hyperglycemia and adiposity are largely recognized as a risk factors for worse disease, vitamin D deficiency might be identified as a novel pathophysiological mechanism involved as common denominator of the endocrine phenotype that negatively influence COVID-19 patients outcomes,” wrote investigators.

With early studies suggesting low levels of vitamin D might predispose patients to greater disease severity with COVID-19, a team led by Prof. Andrea Giustina, of the Division of Endocrinology at San Raffaele Hospital, performed the current study with the intent of addressing an apparent lack of data related to potential associations between vitamin D and blood glucose and BMI in patients with COVID-19. To do so, investigators designed the current study as a retrospective analysis of the COVID-BioB study, which was a prospective observational study carried out at San Raffaele University Hospital and collected data from more than 150 patients admitted with COVID-19 from March 18-May 5, 2020.

After eliminating those with missing information, those using vitamin D supplements, and those affected by osteoporosis or osteopenia, investigators identified a cohort of 88 patients with COVID-19 for inclusion in their analysis. This cohort had a median age of 56.8 (IQR< 49.2-67.5) years, a median BMI of 27 (IQR, 24.7-30.5) kg/m2, and 67% were male.

Overall, this cohort also had a median vitamin D level of 16.3 ng/mL and vitamin D deficiency was identified in 68.2% of patients. Investigators also noted vitamin D deficiency was more common among male patients and those with severe COVID-19.

For the purpose of analysis, vitamin D deficiency was defined as a 25[OH]D level below 20 ng/mL. Investigators noted WHO classification and American Diabetes Association definitions were used to define overweight and hyperglycemia, respectively.

Upon analysis, results indicated severe COVID-19 was present in 7 of 24 (29%) of patients with normal blood glucose levels and normal vitamin D levels. In comparison, severe COVID-19 was observed in 24 of 39 (61%) of patients with hyperglycemic or vitamin D deficiency and in 19 of 25 (76%) of those with both (P=.003). Additionally, investigators pointed out those without hyperglycemic and vitamin D deficiency had greater PaO2:FiO2 and lower N/L ratio, lactate dehydrogenase (LDH), hsCRP, IL-1β, and IL-6 levels.

Analysis revealed severe COVID-19 was observed among 3 of 9 (33%) patients considered normal weight and with normal vitamin D levels, among 11 of 18 (61%) patients with overweight or vitamin D deficiency, and among 23 of 32 (72%) patients with both overweight and vitamin D deficiency (P=.1). Additional analysis indicated greater PaO2:FiO2 ratio and decreased IL-6 levels were observed in those without overweight and vitamin D deficiency compared to those with one or both conditions (371 vs 243 vs 211; P=.03) (8.7 vs 24.3 vs 43.8 pg/mL; P=.046).

Comparison of baseline characteristics, inflammatory parameters, and disease outcomes indicated patients with vitamin D deficiency experienced worse inflammatory response with increased N/L ratio, hsCRP, and LDH compared to patients with overweight, but there were no statistically significant differences observed in baseline characteristics and disease outcomes between these groups.

This study, “Vitamin D levels associate with blood glucose and BMI in COVID-19 patients predicting disease severity,” was published in the Journal of Clinical Endocrinology & Metabolism.