APOE and type 2 diabetes mellitus: In a logistic regression model adjusted also for age and sex, the ApoE ε4ε4 homozygous genotype was found to be associated with an increased risk of developing COVID-19 vs. ε3ε3 homozygotes (Table 3), preserving its statistical significance after the exclusion of participants related to the third degree or closer, and patients carrying ε4 with dementia, hypertension, cardiovascular disease, and type 2 diabetes.