A hospital-based study from China has identified a significant association between vitamin A deficiency (VAD) and the presence and severity of diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM). The cross-sectional and follow-up study evaluated 1,020 patients with T2DM and 470 healthy controls over a five-year period (2019–2024), measuring serum vitamin A using high-precision LC-MS/MS (liquid Chromatography tandem mass spectrometry).
The findings show that 44 percent of participants had vitamin A levels below 1.0 μmol/L, indicating deficiency. Notably, T2DM patients with DR had significantly lower vitamin A levels than both healthy controls and T2DM patients without DR. In multivariate logistic regression, VAD emerged as a predictive factor for DR, even after adjusting for confounders such as age, BMI, hypertension, insulin use, and HbA1c.
Stratification by DR severity revealed a dose-response trend: patients with proliferative DR (PDR) had the highest prevalence of VAD (75.9 percent), compared to those with severe non-proliferative DR (63.2 percent) and moderate/mild cases. Subgroup analysis showed stronger associations in patients who smoked, had hypertension, or elevated HbA1c levels.
A two-year follow-up of DR-free T2DM patients found that each standard deviation increase in vitamin A was associated with a 9 percent reduced risk of developing DR. Moreover, deficient vitamin A levels conferred a 1.73-fold increased risk of DR among patients in the highest quartile of follow-up duration.
Vitamin A is known to suppress VEGF-mediated angiogenesis, inhibit pro-inflammatory cytokine expression, and reduce fibrotic responses – all key components in the pathogenesis of DR. While previous studies offered conflicting evidence, this investigation strengthens the hypothesis that VAD may act as a modifiable biological risk factor for DR.
However, despite the robust design the authors acknowledge limitations in their study, including the cross-sectional nature, the lack of dietary vitamin A intake data, and possible reverse causality. Nonetheless, these findings suggest that vitamin A screening could be used to help identify T2DM patients with elevated risk of DR.
