Serum Vitamin B۱۲, Vitamin D, and Zinc Status in Pediatric Diabetes and Their Association with Diabetic Retinopathy: A Narrative Review

Background: Diabetic retinopathy (DR) is a leading microvascular complication of diabetes mellitus and is increasingly seen in children and adolescents due to rising rates of type ۱ (T۱DM) and type ۲ diabetes (T۲DM). Micronutrients such as vitamin B۱۲, vitamin D, and zinc are essential for retinal vascular integrity, oxidative stress regulation, and homocysteine metabolism. Deficiencies in these nutrients have been implicated in DR pathophysiology in adults, but pediatric data are limited and inconsistent. This review summarizes current evidence on serum vitamin B۱۲, vitamin D, and zinc in pediatric diabetes and their links to DR. Methods: A systematic search was conducted in PubMed, Scopus, and Web of Science for studies published from January ۲۰۰۰ to April ۲۰۲۵. Search terms were applied to titles and abstracts combining "Type ۱ Diabetes Mellitus," "Type ۲ Diabetes Mellitus," or "Pediatric Diabetes" with "Vitamin B۱۲," "Vitamin D," or "Zinc," and "Diabetic Retinopathy." Studies were eligible if they included participants younger than ۱۸ years with T۱DM or T۲DM, reported serum measurements of at least one of the micronutrients, and assessed DR using established diagnostic criteria. Exclusions were the absence of serum biomarker data, lack of DR assessment, non-human studies, case reports, and reviews. Two reviewers independently screened records; of ۳۱۲ identified, ۲۷ were reviewed in full, and ۱۱ met all criteria. Results: Current evidence on micronutrients and DR in pediatric diabetes is limited but growing. Most studies report high prevalence of vitamin D deficiency in children with diabetes, with some linking low levels to early retinal changes, though findings are inconsistent. Vitamin B۱۲ deficiency may increase microvascular risk via elevated homocysteine and oxidative stress, but pediatric data are sparse. Evidence on zinc is mixed, with some studies showing antioxidant and anti-angiogenic effects, while others find no association. Heterogeneity in diagnostic criteria, assays, and populations likely contributes to inconsistent results. Conclusion: Available literature suggests a possible but incompletely defined role of vitamin B۱۲, vitamin D, and zinc deficiencies in pediatric DR. Larger, longitudinal studies with standardized definitions and confounder adjustment are needed. Until then, routine monitoring and timely correction of these micronutrients may be a reasonable preventive approach.