We also tested the influence of the Alzheimer’s disease risk gene variant apolipoprotein E ε4 (APOE ε4) burden on the associations, as this may further increase dementia risk in persons with type 2 diabetes.17 A secondary ‘aim’ was to investigate causal associations between type 2 diabetes and dementia through MR analyses. Here, APOE is linked to early-onset autosomal dominant Alzheimer disease.