Excerpted from page 53 of the September 2015 edition of AOA Focus.
Through his years treating patients with diabetes, A. Paul Chous, O.D., has advised plenty of patients on using supplementation to slow or prevent diabetic retinopathy.
"There are so many nutrients and compounds that may play a part and have shown some success in animal models or small human trials with single nutrients," says Dr. Chous, optometric representative to the National Diabetes Education Program of the National Institutes of Health. "We wanted to move this into something more substantial, with a multicomponent nutritional supplement."
The result is "The Diabetes Visual Function Supplement Study," published online in June 2015 in the British Journal of Ophthalmology. Dr. Chous and colleagues performed a 6-month randomized, controlled trial in 67 adults, all with type 1 or type 2 diabetes. Participants had either no diabetic retinopathy or mild to moderate nonproliferative diabetic retinopathy, and all had no significant differences on key study measures at baseline.
The supplement contained a mix of vitamins and nutrients tied to inhibiting retinopathy in previous work. For instance, benfotiamine, a lipid-soluble analog of vitamin B1, has been shown to shunt glucose metabolites away from the biochemical pathways involved in diabetic retinopathy. Other constituents included Pycnogenol, lipoic acid, vitamin D3, curcumin extract, and zeaxanthin and lutein.
At six months, study participants taking the supplement had better visual function (contrast and visual field sensitivity, and color vision) than those taking placebo, had improvements in serum lipid measures and hsCRP (95% p-values all equal to or less than 0.01), and also showed significant improvements in symptoms related to diabetic peripheral neuropathy.
"In animal models, the same test formula prevented retinopathy without affecting blood glucose levels," Dr. Chous says. "In our trial, we improved abnormal visual function that precedes diabetic retinopathy without affecting hemoglobin-A-1c. We believe we may well be disrupting the biological mechanisms underlying diabetic retinopathy."
The next step will be advancing research with retinal specialists treating patients with sight-threatening disease, such as diabetic macular edema, and supplementing patients over longer periods of time.
"We also want to know whether supplementation is more effective for different stages of disease," he says. "If our hypothesis that this is a harbinger of issues down the road is true, the greatest benefit may be to patients before they get sight-threatening disease."
Learn more about how to talk to your patients about nutrition.
The AOA and other eye care organizations collaborated with the American Diabetes Association to develop an interprofessional communication protocol intended to improve eye health outcomes.
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