Aim: Results from meta-analyses point to an association between vitamin D deficiency and the onset of diabetic retinopathy (DR). The objectives of the present study were to evaluate the association of vitamin D for the development of DR and to determine the levels of vitamin D associated with a greater risk of DR. Methods: Between November 2013 and February 2015, we performed a case-control study based on a sample of patients with diabetes in Spain. The study population comprised all patients who had at least one evaluable electroretinogram and recorded levels of 25(OH)D. We collected a series of analytical data: 25(OH)D, 1,25(OH)2D, iPTH, calcium, albumin, and HbA1c. Glycemic control was evaluated on the basis of the mean HbA1c values for the period 2009–2014. A logistic regression analysis was performed to identify the variables associated with DR. Results: The final study sample comprised 385 patients, of which 30 (7.8%) had DR. Significant differences were found between patients with and without DR for age (69.54 vs. 73.43), HbA1c (6.68% vs. 7.29%), years since diagnosis of diabetes (10.9 vs. 14.17), level of 25(OH)D (20.80 vs. 15.50 ng/mL), level of 1,25(OH)2D (35.0 vs. 24.5 pg/mL), treatment with insulin (14.9% vs. 56.7%), hypertension (77.7% vs. 100%), cardiovascular events (33.2% vs. 53.3%), and kidney failure (22.0% vs. 43.3%). In the multivariate analysis, the factors identified as independent risk factors for DR were treatment of diabetes (p = 0.001) and 25(OH)D (p = 0.025). The high risk of DR in patients receiving insulin (OR 17.01) was also noteworthy. Conclusions: Levels of 25(OH)D and treatment of diabetes were significantly associated with DR after adjusting for other risk factors. Combined levels of 25(OH)D < 16 ng/mL and levels of 1,25(OH)2D < 29 pg/mL are the variables that best predict the risk of having DR with respect to vitamin D deficiency. The risk factor with the strongest association was the treatment of type 2 diabetes mellitus. This was particularly true for patients receiving insulin, who had a greater risk of DR than those receiving insulin analogues. However, further studies are necessary before a causal relationship can be established.

Nursing home residents (NHR) have been targeted as a vaccination priority due to their higher risk of worse outcome after COVID-19 infection. The mRNA-based vaccine BTN2b2 was first approved in Europe for NHRs. The assessment of the specific vaccine immune response (both humoral and cellular) at long term in NHRs has not been addressed yet. A representative sample of 624 NHR subjects in Northern region of Spain was studied to assess immune response against full vaccination with BTN2b2. The anti-S1 antibody levels and specific T cells were measured at two and six months after vaccination. 24.4% of NHR had a previous infection prior to vaccination. The remaining NHR were included in the full vaccination assessment group (FVA). After two months, a 94.9% of the FVA presented anti-S1 antibodies, whereas those seronegative without specific cellular response were 2.54%. At long-term, the frequency of NHR within the FVA group with anti-S1 antibodies at six months were 88.12% and the seronegative subjects without specific cellular response was 8.07%. The cellular immune assays complement the humoral test in the immune vaccine response assessment. Therefore, the cellular immune assessment in NHRs allows for the fine tuning of those seronegative subjects with potential competent immune responses against the vaccine.