Vitamin D deficiency may increase risk of diabetic retinopathy

A new study published in Clinical Nutrition ESPEN showed that insufficient vitamin D levels elevate the risk of retinopathy in individuals with type 2 diabetes. Moreover, in instances of vitamin D deficiency, retinopathy may progress to the proliferative diabetic retinopathy (PDR) type.

Diabetic retinopathy (DR) diagnosis involves identifying clinical signs of abnormal retinal vascularity. Clinically, DR manifests in two stages: non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy. Low vitamin D levels have been linked to impaired insulin secretion and function, leading to suboptimal glycemic control and an increased risk of DR development and progression.  Thereby, this study investigated the links between vitamin D deficiency and the risk of DR progression in individuals with type 2 diabetes mellitus (T2DM).

This case-control study involved 201 participants with DR as cases and 201 individuals with T2DM without DR as controls. Demographic variables were gathered through interviews with a questionnaire, and anthropometric measures followed a standard protocol. Additionally, biochemical indices, including 25-hydroxyvitamin D, fasting blood glucose (FBG), insulin, glycosylated hemoglobin (HbA1c), total cholesterol (TC), LDL-C, HDL-C, and triglyceride (TG), were assessed for all participants.

Through statistical analysis of age, sex, and BMI, no significant differences were found between the two groups. However, the mean concentration of 25-hydroxyvitamin D was considerably lower in the case group compared to the control group (14.46 vs. 19.88).

Additionally, lower vitamin D levels are linked to diabetic retinopathy and proliferative diabetic retinopathy in individuals with type 2 diabetes mellitus.

This study indicates that vitamin D deficiency in individuals with type 2 diabetes mellitus elevates the likelihood of developing diabetic retinopathy and potentially progressing to proliferative diabetic retinopathy.

Reference: 

Zahedi, M., Motahari, M. M., Fakhri, F., Aphshari, N. M., Poursharif, S., Jahed, R., & Nikpayam, O. (2024). Is vitamin D deficiency associated with retinopathy in type 2 diabetes mellitus? A case-control study. In Clinical Nutrition ESPEN (Vol. 59, pp. 158–161). Elsevier BV. https://doi.org/10.1016/j.clnesp.2023.11.011