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.

ResumenObjetivosEvaluar la prevalencia, severidad y factores de riesgo asociados a la retinopatía diabética (RD) en Cantabria.DiseñoEstudio transversal de base poblacional.EmplazamientoCentro de salud de Cantabria.ParticipantesMuestra aleatoria de 442 pacientes con diabetes mellitus tipo 2.Mediciones principalesRetinografía no midriática, clasificándolas según la International Clinical Diabetic Retinopathy Disease Severity Scale. Los factores de riesgo estudiados: edad, sexo, edad diagnóstico, años de evolución de la diabetes, grado de control glucémico (HbA1c), tratamiento de la diabetes, control de la tensión arterial, control lipídico, obesidad, tabaquismo, hematocrito bajo, embarazo, déficit de vitamina D, nefropatía y eventos cardiovasculares.ResultadosPrevalencia de RD del 8,56% (IC: 5,81-11,32). RD no proliferativa leve: 5,07% (IC: 2,89-7,25); RD no proliferativa moderada: 1,38% (IC: 0,17-2,60); RD no proliferativa severa: 0,27% (IC: 0,006-1,28); RD proliferativa: 1,84% (IC: 0,46-3,22); edema macular diabético: 2,30% (IC: 0,77-3,83). Edad media: 70 años, edad de diagnóstico 58,97 años; índice de masa corporal 29,86; hipertensos 78,40%; dislipidemia 67,30% y HbA1c mediana 6,76%. El déficit de 25 (OH) D fue del 77%. En el análisis multivariante los factores independientes fueron tratamiento de la diabetes mellitus tipo 2, índice de masa corporal, años de evolución y control de la diabetes.ConclusionesLa prevalencia de RD ha disminuido hasta el 8,56%; esta disminución se asocia a la mejora en el control de los factores de riesgo modificables. Los factores de riesgo asociados de forma independiente fueron: tratamiento, índice de masa corporal, años de evolución y control de la diabetes. Las variables control hipertensión arterial, eventos cardiovasculares y nefropatía también mostraron capacidad predictiva para la RD.