The study looked at sodium-glucose cotransporter-2 (SGLT2) inhibitors, which are also known as gliflozins. They lower blood sugar by causing the kidneys to remove sugar from the body through urine.

“We know that these neurodegenerative diseases like dementia and Parkinson’s disease are common and the number of cases is growing as the population ages, and people with diabetes are at increased risk of cognitive impairment, so it’s encouraging to see that this class of drugs may provide some protection against dementia and Parkinson’s disease,” said study author Minyoung Lee, MD, PhD, of Yonsei University College of Medicine in Seoul, South Korea.

The retrospective study looked at people with type 2 diabetes who started diabetes medication from 2014 to 2019 in South Korea. People taking SGLT2 inhibitors were matched with people taking other oral diabetes drugs, so the two groups had people with similar ages, other health conditions and complications from diabetes. Then researchers followed the participants to see whether they developed dementia or Parkinson’s disease. Those taking the SGLT2 inhibitors were followed for an average of two years and those taking the other drugs were followed for an average of four years.

Among the 358,862 participants with an average age of 58, a total of 6,837 people developed dementia or Parkinson’s disease during the study.

For Alzheimer’s disease, the incidence rate for people taking SGLT2 inhibitors was 39.7 cases per 10,000 person-years, compared to 63.7 cases for those taking other diabetes drugs. Person-years represent both the number of people in the study and the amount of time each person spends in the study.

For vascular dementia, which is dementia caused by vascular disease, the incidence rate for people taking the SGLT2 drugs was 10.6 cases per 10,000, compared to 18.7 for those taking the other drugs.

For Parkinson’s disease, the incidence rate for those taking the SGLT2 drugs was 9.3 cases per 10,000, compared to 13.7 for those taking the other drugs.

After researchers adjusted for other factors that could affect the risk of dementia or Parkinson’s disease, such as complications from diabetes and medications, they found that SGLT2 inhibitor use was associated with a 20% reduced risk of Alzheimer’s disease and a 20% reduced risk of Parkinson’s disease. Those taking the drugs had a 30% reduced risk of developing vascular dementia.

“The results are generally consistent even after adjusting for factors like blood pressure, glucose, cholesterol and kidney function,” Lee said. “More research is needed to validate the long-term validity of these findings.”

Lee said that since participants were followed for less than five years at the most, it’s possible that some participants would later develop dementia or Parkinson’s disease.

The study was supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health & Welfare of Korea; Severance Hospital; and Yonsei University College of Medicine.