Multi-target ocular protection of blueberry anthocyanins in elderly type 2 diabetes: An exploratory clinical investigation

Abstract With the increasing prevalence of diabetic retinopathy (DR), there is an urgent need for interventions offering both metabolic and ocular benefits. This initial clinical exploration investigated the intervention effects of blueberry anthocyanins in elderly type 2 diabetic patients over six months. Supplementation with blueberry anthocyanin extract (BAE, 400 mg/day) showed favorable changes in ocular functions, with improved visual acuity (as reflected by negative ΔlogMAR values), reduced intraocular pressure (IOP∼8%, P < 0.05), and restored retinal structural integrity, which was evidenced by decreased macular edema and retinal thickness via optical coherence tomography (OCT) imaging. Furthermore, patients reported a notable alleviation of visual fatigue symptom, such as eye soreness (P < 0.05) and lacrimation (P < 0.01). Correlating with the observed ocular protection, BAE also improved systemic metabolic parameters such as fasting blood glucose and glycated hemoglobin (HbA1c) (P < 0.01), insulin resistance (triglyceride-glucose index), and inflammation markers (such as neutrophil-to-lymphocyte ratio and monocyte-to-lymphocyte ratio). These findings should be interpreted as preliminary associations, as concurrent medications were not systematically controlled. Nonetheless, they tentatively indicated the dual action of blueberry anthocyanins for simultaneously targeting metabolic dysregulation and DR-associated visual impairment, providing clinical evidence for its development as a promising functional food used in adjunct therapy for diabetic patients.