Estimated association between baseline categories of diabetes and 20-year cognitive decline by diabetes, HbA1c, and 1,5-AG group. Estimates and 95% CIs are from linear mixed-effects models with adjustment for age, age squared, race–field center, sex, education, cigarette smoking status, drinking status, hypertension, history of stroke, history of coronary heart disease, APOE4 genotype, BMI, and interactions between these variables and time. Time since baseline (visit 2) was the time axis and was modeled with a linear spline with a knot at 6 years. A random intercept and two random slopes for time (one for each spline term) were included, and the three random effects were assumed to be independent. Slope: dashed lines indicate linear regression fit across the three diabetes groupings (no diabetes, diabetes HbA1c <7%, diabetes HbA1c ≥7%) and 1,5-AG category by creating an indicator that takes on the values 1, 2, or 3. Decline indicates the estimated 20-year cognitive decline per category. The P values comparing 1,5-AG concentrations ≥10 to <10 μg/mL are from analyses stratified by diabetes group (no diabetes, diabetes with HbA1c <7%, diabetes with HbA1c ≥7%) with additional adjustment for HbA1c. An HbA1c of 7% is equivalent to 53 mmol/mol.