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Diabetes affects every system in the body, but the eyes are among the most vulnerable. Diabetic retinopathy — damage to the blood vessels of the retina — is one of the leading causes of preventable blindness worldwide. Understanding how it develops, and how omega-3 fatty acids may help slow it, starts with understanding the smallest structures in the body.
How the Eye Gets Its Blood Supply
Arteries carry oxygenated blood from the heart to every organ. As they approach their destination, they divide into progressively smaller vessels until they become capillaries — single-cell-thick tubes through which nutrients, oxygen, and waste products are freely exchanged. These capillaries are the final connection between the blood and the cells they nourish.
Because capillaries are so delicate, they are supported by specialised cells called pericytes — structural scaffolding that keeps the capillary walls intact and regulates the flow of substances in and out of the tissue.
What Diabetes Does to Pericytes
Pericytes are extremely sensitive to blood sugar levels. Every time they are exposed to excess glucose — which happens repeatedly in uncontrolled diabetes — they swell. When sugar drops, they shrink. This repeated cycle of expansion and contraction is physically and biochemically damaging. Over time, pericytes begin to die.
Initially, surrounding cells compensate by expanding. But once that limit is reached, gaps form in the capillary wall. Capillaries — unable to maintain their own structure without pericyte support — either collapse or burst.
What Happens to the Retina
As retinal capillaries progressively collapse, increasing areas of the retina stop receiving adequate blood flow. Oxygen-starved retinal cells send out chemical distress signals — most importantly, VEGF (vascular endothelial growth factor).
VEGF triggers an emergency response: the retina sprouts new blood vessels. But these new vessels are fragile, poorly formed, and located in the wrong place. They eventually burst or shrink, causing bleeding within the eye, retinal detachment, or both. This is end-stage diabetic retinopathy.
Where Omega-3 Fatty Acids Help
Stabilising Pericyte Cell Membranes
Omega-3 fatty acids are normal components of cell membranes. A higher proportion of omega-3 in pericyte membranes makes those membranes more pliable, resilient, and better able to manage the transport of glucose across them. This reduces the physical and biochemical stress that damages pericytes in high-sugar environments.
Reducing Oxidative and Inflammatory Stress
Omega-3 fatty acids support the formation of anti-inflammatory mediators — including resolvins and protectins — that reduce cellular damage caused by elevated blood glucose. They also enhance antioxidant defences that protect pericytes from the oxidative stress that high sugar generates.
An Important Caveat
Omega-3 fatty acids support healthy microvascular function — but they do not replace blood sugar control. Without adequate glucose management through diet, exercise, and medication, no supplement can meaningfully protect against the progression of diabetic complications. Omega-3s work best as part of a comprehensive approach to diabetes management.
References
- Warmke N, Griffin KJ, Cubbon RM. Pericytes in diabetes-associated vascular disease. J Diabetes Complications. 2016.
- An Y, et al. Oxidative stress in diabetes mellitus-induced vascular endothelial dysfunction. Cardiovasc Diabetol. 2023.
- Sahin Bayram S, Kiziltas G. Omega-3 PUFAs in diabetes mellitus management. Curr Nutr Rep. 2024.
Sivri D, Akdevalioglu Y. Fatty acids, glucose metabolism and type 2 diabetes. Nutr Rev. 2025.
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