Blood glucose and red light

There’s been increasing interest in photobiomodulation and muscles.

Researchers from Brazil have been looking further into this, curious to see what happens to blood glucose (often called blood sugar) when a combination of red and near infrared light is shone into muscles. Their interest was piqued by reports that photobiomodulation can help lower blood glucose levels in people with diabetes. Blood glucose levels stay high in diabetes and that causes all sorts of problems for the rest of the body.

Twenty four rats were all living in the same conditions. One, three and six hours after a meal, they all had their blood sugars measured. They were split into four groups, and each group had a different dose of light, lasting ninety seconds. There was a control group, which received zero light, and three other groups, each receiving different doses of light.

The results are fascinating, especially from one to three hours after the rats’ meal. Blood glucose levels in the control group (zero light) stayed the same for those two hours. In the three groups with light doses, the blood glucose levels dropped. The biggest drop was the group who had the lowest dose of light.

At the six hour mark, the control group still had a higher blood glucose level than any of the treated groups. As before, the group with the lowest dose of light had the lowest blood glucose reading.

During the six hours, the rats weren’t exercising or eating, and they were all living in the same conditions with plenty of access to water. The only difference was the amount of light dose received. The blood glucose response in the control group was significantly different to the light groups.

After 24 hours, the level of glycogen in muscle cells was measured. Glycogen is a fuel store, and the more glycogen in the muscle cell, the longer the muscle cell can keep going. The control group didn’t have much glycogen compared with the light groups which means that the photobiomodulation had stimulated the creation and storage of glycogen in the muscle cell. That’s impressive.

These two findings are really something. The authors comment that this study has shown that shining red and near infrared light into muscle groups seems to improve the whole body’s ability to take glucose out of the bloodstream and store it where it is needed.

Given that diabetes is increasing in prevalence across the world (in 1980 4.7% of people over eighteen had diabetes; in 2014 it had risen to 8.5%), this study brings hope for those with or at risk of diabetes.


1. Kenia Mendes Rodrigues Castro, Rodrigo Leal de Paiva Carvalho, Geraldo Marco Rosa Junior, Beatriz Antoniassi Tavares, Luis Henrique Simionato, Carlos Henrique Fachin Bortoluci, Claudio Alberto Tellez Soto, Cleber Ferraresi, Can photobiomodulation therapy (PBMT) control blood glucose levels and alter muscle glycogen synthesis?, Journal of Photochemistry and Photobiology B: Biology, Volume 207, 2020.

2. World Health Organisation.

Author: RedlightsontheBrain

Redlightsonthebrain is written by Catherine Hamilton, a retired doctor on behalf of Light Ahead Inc, a Tasmanian-based not-for-profit organisation. Light Ahead Inc aims to help people to learn about neurogenerative diseases and the practical, safe and scientifically-based things that may be able to help. Part of this is to provide low-cost access to red light devices, hence the DIY instructions on this blog. All sales of the Coronet red light device support the work of Light Ahead Inc.