A well-known diabetes drug could be used to help people who suffer from Parkinson’s disease. Researchers have concluded a year-long study and discovered that people who took exenatide weekly had better motor functions compared to a control group.

The study, published in The Lancet, followed 60 people with Parkinson’s disease. Thirty-one of them had an injection of exenatide once a week for 48 weeks, while the rest received a placebo injection. People on exenatide performed better in motor tests at the end of the trail compared to the control group. They were then tested again 12 weeks later, with the people on exenatide still performing better.

“This is a very promising finding, as the drug holds potential to affect the course of the disease itself, and not merely the symptoms,” senior author Professor Tom Foltynie, from University College London, said in a statement. “With existing treatments, we can relieve most of the symptoms for some years, but the disease continues to worsen.”

The patients in the drug group did not report a significant improvement in their day-to-day life compared to the current treatment. It also needs to be clear that the research didn’t conclusively prove that exenatide was actually affecting the disease, it might simply be reducing its symptoms.

“While we are optimistic about the results of our trial, there is more investigation to be done, and it will be a number of years before a new treatment could be approved and ready for use. We also hope to learn why exenatide appears to work better for some patients than for others,” said the study’s first author, Dr Dilan Athauda from UCL's Institute of Neurology.

Exenatide has been used since 2005 to treat Type 2 diabetes. It activates receptors in the pancreas that stimulates insulin release. The same receptors are found in the brain where they improve the function of dopamine connections. Symptoms for Parkinson’s only become apparent after 70 percent of the brain’s dopamine-producing cells have been affected by the condition, so that's where the drug's effect comes into play.

“Using approved therapies for one condition to treat another, or drug repurposing, offers new avenues to speed Parkinson’s therapeutic development,” said Dr Brian Fiske, senior vice president of research programs at the Michael J Fox Foundation, set up by the actor who suffers from the disease, which funded the study. “The results from the exenatide studies justify continued testing, but clinicians and patients are urged not to add exenatide to their regimens until more is known about their safety and impact on Parkinson’s.”

More than 10 million people are currently living with Parkinson’s disease, making it the second most common neurodegenerative condition in the world.