By Robert Preidt
Researchers compared the medical records of those diabetes patients against the records of more than 120,000 diabetes patients who did not take a glitazone. The investigators tracked these records from 1999 -- when glitazones were introduced to treat diabetes -- until 2013.
During that time, patients who used glitazones were 28 percent less likely to be diagnosed with Parkinson's disease than those who never took one of the meds, the study found. This association between glitazones and lower risk of Parkinson's remained even after the researchers adjusted for known predictors of Parkinson's, such as smoking and head injury.
However, when the investigators looked at past and current glitazone users separately, they found that the lower risk of Parkinson's was seen only in people currently using a glitazone (a 41 percent lower risk of Parkinson's), not in those who had previously used glitazones but had stopped or switched to another class of diabetes drugs.
This suggests that any benefit wears off once a person goes off the drugs, according to the team led by Dr. Ruth Brauer of the London School of Hygiene & Tropical Medicine, in London.
Dr. Minisha Sood is a diabetes expert and an endocrinologist at Lenox Hill Hospital in New York City. She called the new finding "an exciting development because it suggests that glitazones may prevent the onset of Parkinson's disease in patients with diabetes."
However, "more studies are needed to confirm this finding," she added, "and studies in non-diabetic patients should be conducted to examine whether glitazone medications would be effective for that population in the prevention of Parkinson's disease."
The study was funded by the Michael J. Fox Foundation for Parkinson's Research and was published July 21 in the journal PLoS Medicine.
While the study can't prove cause and effect, the researchers said the findings are in line with prior animal and laboratory tests showing that glitazones might help protect the brain.