In addition, this is an observational study, and there are unmeasured variables (eg, social determinants of health, food insecurity, diabetes self-care behaviors, and APOE4 [OMIM 107741] mutation) that are not available in electronic health records that may confound the observed findings.16 Comorbidities, complications, and outcomes were determined by coding of encounters, which may be influenced by treatment setting.41 Study eligibility required at least 4 HbA1c tests during the 3-year baseline period, which may select for individuals with greater contact with the health care system. This evidence concerns the gene APOE and diabetes mellitus.