APOE and diabetes mellitus: In the studies with paediatric participants, Liu et al.23 compared the proportion of cognitive impairment by sociodemographic factors (e.g., gender, age, educational qualification, ethnicity, and income level), and clinical conditions and medical histories (e.g., Apoe4, smoking history, drinking history, BMI, history of hypertension, and diabetes) and Slykerman et al.22 adjusted for potential confounders including treatment group assignment, mode of delivery, breastfeeding and income.