A team of American researchers has linked diabetes, vitamin A deficiency and early vision loss, a hallmark of diabetic retinopathy. By increasing their vitamin A intake, patients could not only improve their eyesight, but also prevent this pathology.

New study highlights how vitamin A supplementation could improve eyesight in diabetic patients. Researchers from the University of Oklahoma (United States) have just established a link between diabetes, vitamin A deficiency and early vision loss, characteristic of certain cases of diabetic retinopathy, a serious complication of diabetes. type 2 which can cause visual blindness.

Their work, published in the specialized journal The American Journal of Pathology (1), indicates that richer daily intakes of vitamin A would help preserve the sight of diabetics. A discovery which - if confirmed - could significantly improve the daily lives of the approximately 442 million people suffering from diabetes worldwide (2).

As a reminder, diabetic retinopathy affects approximately 50% of type 2 diabetic patients and is one of the main causes of blindness after the age of 65. It is caused by the excess of sugar in the blood (chronic hyperglycemia) which weakens the wall of the latter, causing a loss of tightness and the bursting of small blood vessels of the retina, recalls the French Federation of diabetics (3 ).

Patients with diabetes often notice functional vision deficits before a pathology is detected: poor adaptation to darkness, sensitivity to light contrast and difficulty perceiving colors.
Vitamin A, essential for the proper functioning of our eyes

To reach this conclusion, the scientists studied three groups of 3-month-old mice: a first group (composed of diabetic mice) received an injection based on the visual cis-retinal chromophore 9 - a vitamin A analogue. The second group (also made up of diabetic mice) received placebo treatment. The third group (composed of healthy mice) served as a "control group".

"In a previous study, we found that diabetes causes a deficiency of vitamin A in the retina, which leads to deterioration of vision, even before vascular changes are visible. This discovery led to the hypothesis that the early vision changes in diabetes are probably caused by a deficiency of vitamin A in the retina, "said Dr. Gennadiy Moiseyev, the study's main instigator.

The results showed that the visual function in the diabetic mice of the first group (who received vitamin A supplementation) improved significantly after the treatment. In addition, researchers have reported that the treatment reduces oxidative stress in the retina, decreases the death of retinal cells and degeneration of the retina, and improves visual function.

"This work supports our new hypothesis that the diabetes-induced disruption of vitamin A metabolism in the eye is responsible for reduced visual function in the early stages of diabetic retinopathy," said the researchers.

"Currently, there is no therapy available to prevent the development of the retinal complication in patients suffering from diabetes, recalls Dr. Gennadiy Moiseyev.

This discovery could contribute to the development of a new therapeutic strategy from the early stages of diabetic retinopathy in order to prevent vision loss in diabetic patients, conclude the researchers. But more studies will be needed to confirm these observations.