Opposite effects of sulfonylureas, TZDs versus metformin
The study authors analyzed 559,106 VA patients with type 2 diabetes who initiated glucose-lowering medication during 2001-2017 and took it for at least a year. They were aged 60 years or older and did not have dementia at baseline. Most were White (76.8%) and male (96.9%), two-thirds (63.1%) had obesity, and mean hemoglobin A1c was 6.8%.
Overall, 31,125 developed all-cause dementia. The incidence rate was 8.2 cases per 1,000 person-years, ranging from 6.2 cases per 1,000 person-years among those taking metformin monotherapy to 13.4 cases per 1,000 person-years in those taking both sulfonylurea and a TZD.
Compared with metformin monotherapy, the hazard ratio for all-cause dementia for sulfonylurea monotherapy was a significant 1.12. The increased risk was also seen for vascular dementia, with an HR of 1.14.
In contrast, TZD monotherapy was associated with a significantly lower risk for all-cause dementia (HR, 0.78), as well as for Alzheimer’s disease (HR, 0.89) and vascular dementia (HR, 0.43), compared with metformin monotherapy.
The combination of metformin and TZD also lowered the risk of all-cause dementia, while regimens including sulfonylureas raised the risks for all-cause and vascular dementia.
Most of the results didn’t change significantly when the drug exposure window was extended to 2 years.
Effects more pronounced in those with obesity
The protective 1-year effects of TZD monotherapy and of metformin plus TZD, compared with metformin alone, were more significant among participants aged 75 or younger and with a body mass index above 25 kg/m2, compared with those who were older than 75 years and with normal BMIs, respectively.
On the other hand, the greater risk for dementia incurred with sulfonylureas was further increased among those with higher BMI.
This research was partially funded by grants from the National Human Genome Research Institute, the National Science Foundation, the National Institute of Diabetes and Digestive and Kidney Disease, and the National Heart, Lung, and Blood Institute. Dr. Koychev is chief investigator for a trial, sponsored by Oxford University and funded by Novo Nordisk, testing whether the GLP-1 agonist semaglutide reduces the risk for dementia in aging adults.
A version of this article first appeared on Medscape.com.