Additional file 1 of Clarifying the biological and statistical assumptions of cross-sectional biological age predictors: an elaborate illustration using synthetic and real data

Supplementary Material 1

Mean Particle Sizes of LDL and HDL in Individuals from Long-Lived Families and 90-y-Old Singletons from the General Population

<div><p>(A) LDL; (B) HDL.</p> <p>* <i>p</i> ≤ 0.02 for comparison versus partners (controls); ** <i>p</i> ≤ 10⁻³ for comparison versus partners (controls).</p></div

Study Design

<p>Long-lived families were recruited if they included a long-lived sibling pair with males aged 89 y or older and women aged 91 y or older.</p

Regression coefficients from the linear regression analysis for the response variable, IgG values, and the covariates age and sex (female = 0, male = 1) after adjustment for the family status.

<p>Only significant results (<i>P<0.05</i>) are depicted. Positive regression coefficients for age indicate increased levels with increasing age, while negative coefficients indicate decreased levels with increasing age. For sex, a positive regression coefficient indicates higher levels for male participants than female participants, while a negative coefficient indicates lower levels for male participants.</p

IgG glycosylation and the interaction between age and sex.

<p>Relationship between age and IgG1 <b>A</b> glycoform, stratified for sex. Males are plotted in blue, with a fitted line in dashed dark blue (A), while females are plotted in orange with a fitted line in continuous dark red (B). Both lines were fitted using the loess (locally weighted scatter plot smoothing) method, and plotted for both males in females (C) to illustrate the crossing slopes.</p

Homocysteine levels in offspring and controls.

<p>Data represent adjusted means with standard error. P-value obtained after correction for family clusters within offspring. Adjusted data obtained after correction for sex, age and creatinine.</p

IgG glycosylation and its association to longevity.

<p>Relationship between age and IgG1 <b>D</b> glycoform, stratified for the family status and younger/older than 60 years. Values from males are plotted in blue, while values from females are plotted in orange. The fitted lines (dashed dark blue for males and continuous dark red for females) are drawn using the loess (locally weighted scatter plot smoothing) method.</p

Logistic regression analysis of non-bisecting/bisecting ratios with the response variable family status.

<p>Age groups are stratified <60 and >60. * the value for glycoform <b>E</b> is already a bisecting/non-bisecting ratio as it is normalized on its non-bisected counterform <b>B</b>.</p

Structures of the N-glycans attached to IgG glycopeptides, as profiled in our analysis.

<p>Compositions and structural schemes are given in terms of <i>N</i>-acetylglucosamine (blue square), mannose (green circle), galactose (yellow circle) and fucose (red triangle).</p

Table_6_High Adiposity Is Associated With Higher Nocturnal and Diurnal Glycaemia, but Not With Glycemic Variability in Older Individuals Without Diabetes.docx

Background<p>It is well known that adiposity is a risk factor for insulin resistance and type 2 diabetes mellitus. In the present study, we aimed to investigate the associations of measures of adiposity with indices of glycemia and of glycemic variability over a 72-h period in non-diabetic older adults.</p>Methods<p>This cross-sectional study was conducted in non-diabetic individuals from the Active and Healthy Aging Study (N = 228), Switchbox (N = 116), and the Growing Old Together Study (N = 94). Body mass index (BMI) and waist circumference were measured, and indices of glycemia and glycemic variability were derived from continuous glucose monitoring (CGM) using the Mini-Med^® CGM system. Associations between adiposity and CGM were studied separately for the three cohorts, and derived estimates were subsequently meta-analyzed.</p>Results<p>After meta-analyzing the results from the separate cohorts, individuals with a higher BMI had higher levels of glycemia. Individuals with BMI between 30 and 35 kg/m² had 0.28 mmol/L [95% confidence interval (CI): 0.12–0.44] higher 72 h-mean glucose concentration, 0.26 mmol/L (0.10–0.42) higher diurnal glucose (6:00 a.m. to 0:00 a.m.), and 0.39 mmol/L (0.19; 0.59) higher nocturnal glucose (3:00 a.m. to 6:00 a.m.) than participants with a normal weight (BMI 18.5–25 kg/m²). However, no associations were observed between higher BMI and glycemic variability. Results for glycemia and glycemic variability were similarly observed for a high waist circumference.</p>Conclusion<p>High adiposity associates with constant higher mean glucose levels over the day in non-diabetic older adults.</p