• Exposure to a therapeutic red light lamp for 15 minutes after a meal lowered blood sugar levels by almost 30 percent in healthy volunteers.
• Red light therapy has been tested in several other conditions, including wound healing and depression.
• It’s not yet clear whether red light therapy can help people with diabetes manage their blood sugar, but researchers hope it could one day be a beneficial add-on therapy.

A specific wavelength of red light, when shone on a person’s back for 15 minutes, can significantly reduce blood sugar levels after meals, according to a new study published on February 20 in the Journal of Biophotonics.^[1]

Researchers found that red light therapy had dual benefits in blood sugar control: A single dose reduced overall blood glucose levels and how high blood sugar levels peaked after a glucose tolerance test, which mimics the body’s response to a meal.

Though the study was conducted in healthy people without diabetes, the treatment — which involves no injections or pills — has the potential for use with diabetes control after meals, according to the lead author, Michael Powner, PhD, a senior lecturer in neurobiology in the school of health and psychological sciences at the City University of London. “This is important, as very high blood glucose levels have the potential to damage tissues around our body,” says Dr. Powner. These fluctuations in blood sugar spikes also contribute to aging, he adds.

The Healing Power of Red Light Has Been Studied in Cancer, Depression, and Many Other Health Conditions

The red light therapy tested in the study is a form of photobiomodulation (PBM), which uses light to stimulate living things into healing themselves.^[2] It’s been studied in many different conditions, including cancer, macular degeneration, depression, wound healing, skin conditions, and different areas of dentistry.

To explore the impact of 670 nanometers (nm) of red light on blood sugar levels, the researchers recruited 30 healthy participants who were not taking any medications and had no known metabolic conditions, including diabetes. They were randomized into two groups of 15 people each.

At the start of the trial, both groups took a fasting oral glucose test to establish a baseline. Participants consumed only water for at least 10 hours, then on an empty stomach drank a syrupy 5 ounce drink that contained 75 grams (g) of sugar. Then they recorded their blood sugar levels every 15 minutes over the next two hours.

Within a week, another blood glucose test was given, this time with one group receiving a 15-minute 670 nm red light exposure on the bare skin of their upper back. Those in the placebo group were positioned identically for 15 minutes, but the light was not turned on.

Red Light Group Had a 12 Percent Reduction in Peak Blood Sugar Levels Compared With Placebo

Researchers found that compared to the baseline, those in the red light group had close to a 28 percent reduction in blood glucose levels following glucose intake, and it reduced maximum glucose spiking by 7.5 percent. Compared with the placebo group, the red light group had a 12 percent reduction in peak blood sugar levels.

“This study showed that in healthy participants without diabetes, short-term photobiomodulation lowered the peak glucose level after an oral glucose tolerance test,” says Marilyn Tan, MD, an associate professor of medicine and an endocrinologist at Stanford Health Care in California who was not involved in the study. The findings suggest that red light therapy for people without diabetes improves glucose tolerance — but it isn’t clear what it would mean for people with diabetes, or what the long-term impacts might be, adds Dr. Tan.

How Red Light Therapy Could Improve Blood Sugar Control

Previous research has established that long-wavelength light between approximately 650 to 900 nm (spanning the visible through to the near-infrared range) can increase mitochondrial production of adenosine triphosphate (ATP), a nucleotide that provides energy for vital cellular processes.

Researchers suspect that increased ATP production could cause signaling changes throughout the body, leading to improvements through what’s known as the “abscopal effect” — when a treatment in one area of the body can cause cellular changes in another part of the body, explains Powner.

“We have chemical messages being sent around in our blood. Previous studies have reported changes to these chemical messages following red light exposure, which could be initiating the change in how glucose is used around the whole body after red light exposure,” he says.

Could Red Light Therapy Be Used to Treat Diabetes and Reduce the Need for Insulin and Medications?

“If the positive effects of red light on glucose levels are validated in larger studies, in people with prediabetes or diabetes, our findings suggest that using red light before meals for a few minutes would likely help reduce the subsequent increase in blood glucose,” says Powner.

Tan agrees more research is needed to expand on these findings. “This was a small study of 30 patients, and again, they were healthy and did not have diabetes at baseline,” she says. Longer term and large studies in people with diabetes must be conducted, which would include longer-term follow-up to better understand how sustained this glucose response is, Tan says.

“We also don’t know how it will impact glucose responses in the setting of other diabetes medications, such as insulin. We also don’t know the long-term impact of repeated exposure to photobiomodulation,” she says.

If the findings were positive in those types of trials in people with diabetes, it could mean that red light therapy could reduce postmeal blood sugar, which might mean these people could use less insulin or fewer diabetes medications, says Tan.