Coffee consumption has a protective effect against the development of diabetic retinopathy, the eye condition that can cause vision loss and blindness, in people with type 2 diabetes, which accounts for 80% of diabetes cases, according to research recently published in the journal Nutrients. The research involved a comparative study of people with and without diabetic retinopathy by answering a dietary questionnaire. An experimental mouse model was also used, in which caffeine was topically administered to the retina.

"Moderate and high caffeine intake was associated with a 65% reduction in the risk of diabetic retinopathy in people with type 2 diabetes without other late diabetic complications. Although these results were not confirmed in the in vivo study in mice," explained IRBLleida researcher Minerva Granado, professor at the University of Lleida (UdL) and at the Centre for Biomedical Research on the Diabetes and Associated Metabolic Diseases Network (CIBERDEM). "This finding allows further progress to be made in research into the impact of ophthalmology on people with diabetes," she said.

Diabetic retinopathy, an ophthalmological complication of diabetes, is the main cause of vision loss and blindness in diabetics. Its incidence is expected to increase due to the growing incidence of diabetes, obesity and an ageing population.

The research has involved the participation of research staff from the Avantmedic Centre of Lleida, the University of Lleida (UdL), the Institute for Biomedical Research of Lleida (IRBLleida), CIBERDEM, the Jordi Gol University Institute for Primary Care Research (IDIAP Jordi Gol), the Vall d'Hebron Research Institute (VHIR), the Washington University School of Medicine, the Arnau de Vilanova University Hospital of Lleida, the University of Lleida, the Institute for Health and Biomedical Research of Lleida (IHBR), the University of Lleida, the University Institute of Health and Biomedical Research of Lleida, the University of Lleida, the University of Lleida, the University of Lleida, the University Institute of Health and Biomedical Research of Lleida, the University of Lleida and the University Hospital of Lleida, the Instituto de Investigación Sanitaria y Biomédica de Alicante (ISABIAL), the CIBER de Epidemiología y Salud Pública (CIBERESP), the Universidad Miguel Hernández de Alicante, the Instituto Alicantino de Investigación Sanitaria y Biomédica (Fundación ISABIAL-FISABIO), the Hospital de la Santa Creu i Sant Pau & Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau) and the Universitat de Vic.

The research studied 144 people with diabetic retinopathy and 147 people without diabetic retinopathy by an experienced ophthalmologist. Research staff administered a validated food consumption frequency questionnaire to people participating in the project. In the experimental model, a total of 20 mice were randomly administered a drop of caffeine directly onto the corneal surface twice daily for two weeks in each eye. The experimental model did not corroborate the findings in humans.

"Further studies are needed to establish the benefits and mechanisms of caffeinated beverages in the development of diabetic retinopathy. It is important to bear in mind that in coffee and other caffeine-containing beverages, there are other compounds that may have a fundamental role in the prevention of these pathologies and, therefore, they need to be studied," explained Minerva Granado, researcher on the project.