Diabetes mellitus and risk of early-onset Alzheimer's disease: a population-based case-control study.

BACKGROUND AND PURPOSE: Previous studies have reported that diabetes is a risk factor for both all-cause and vascular dementia; however, diabetes as a risk factor for Alzheimer's disease (AD) remains controversial. Therefore, the aim was to elucidate the association between diabetes and early-onset AD.

METHODS: A case-control study was conducted using a population-based database that included medical and pharmacy claims and insurance eligibility data, from beneficiaries of corporate employees and their dependent family members. Cases were aged 40-64 years and were first prescribed medications for AD between 2005 and 2016. Up to four controls matched for age, sex and hospital type were included for each case. Data were analyzed using conditional logistic regression and compared between the sexes.

RESULTS: Data from 371 patients with AD (mean age 56.3 ± 5.3 years; 48% female) and 1484 controls were analyzed. Use of antidepressants, antipsychotics and antithrombotics during the index month was higher amongst patients with AD (19.4%, 34.5% and 11.3%, respectively) than amongst controls (2.9%, 10.3% and 7.3%, respectively). Our findings suggest no evidence for an association between diabetes and risk of early-onset AD (adjusted odds ratio 1.31; 95% confidence interval 0.90-1.92). In the subgroup analyses, adjusted odds ratios in patients with diabetes were 0.73 (95% confidence interval 0.38-1.39) and 1.68 (95% confidence interval 1.06-2.67) for female and male patients, respectively.

CONCLUSIONS: There is no apparent association between diabetes and risk of early-onset AD in the total study population, although a weak association was observed amongst male patients.