BACKGROUND: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been shown to decrease blood glucose levels, promote weight loss, and prevent cardiovascular events. However, evidence is limited regarding their effect on dementia, although emerging observational studies, some with serious methodological limitations, have suggested large reductions in dementia associated with GLP-1RAs that may not be entirely causally related.
OBJECTIVE: To compare the effect of GLP-1RAs versus dipeptidyl peptidase-4 inhibitors (DPP4is) as second-line therapy for type 2 diabetes on risk for dementia among older adults.
DESIGN: Target trial emulation.
SETTING: United States from January 2016 to December 2020.
PARTICIPANTS: Medicare fee-for-service beneficiaries aged 66 years or older with diabetes who used metformin and did not have dementia at baseline and initiated GLP-1RAs or DPP4is between January 2017 and December 2018.
MEASUREMENTS: Onset of dementia was defined as 1 year before the date of a new dementia diagnosis. Risks were calculated at 30 months in GLP-1RA and DPP4i groups matched in a 1:2 ratio on an estimated propensity score and compared via ratios and differences.
RESULTS: Among 2418 patients initiating GLP-1RAs and 4836 matched patients initiating DPP4is, the mean age was 71 years, and 55% were female. Over a median follow-up of 1.9 years, the outcome occurred in 96 patients in the GLP-1RA group and 217 in the DPP4i group. The estimated risk difference at 30 months was -0.93 (95% CI, -2.33 to 0.23) percentage points, and the estimated risk ratio was 0.83 (95% CI, 0.61 to 1.05). The estimated risk ratios were 0.64 (95% CI, 0.46 to 0.93) and 1.22 (95% CI, 0.74 to 1.66) among those younger than 75 years and aged 75 years or older, respectively.
LIMITATIONS: Potential residual confounding (no data on body mass index, glycemic control, or duration of diabetes), outcome misclassification, and short follow-up.
CONCLUSION: Among older adults with diabetes, no clear evidence was found that the incidence of dementia differed overall between patients using GLP-1RAs versus DPP4is. Under conventional statistical criteria, an effect of GLP-1RAs between a 39% decrease and a 5% increase in risk for dementia was highly compatible with the data, although estimates differed by age. Randomized trials are needed to quantify the effect of GLP-1RAs on dementia.
PRIMARY FUNDING SOURCE: Gregory Annenberg Weingarten, GRoW @ Annenberg.
