Factor structure analyses have revealed the presence of specific biological
system markers in healthy humans and diseases. However, this type of approach in
very old persons and in type 2 diabetes (T2DM) is lacking. A total sample of
2,137 Italians consisted of two groups: 1,604 healthy and 533 with T2DM. Age
(years) was categorized as adults (≤65), old (66-85), oldest old (>85-98) and
centenarians (≥99). Specific biomarkers of routine haematological and biochemical
testing were tested across each age group. Exploratory factorial analysis (EFA)
by principal component method with Varimax rotation was used to identify factors
including related variables. Structural equation modelling (SEM) was applied to
confirm factor solutions for each age group. EFA and SEM identified specific
factor structures according to age in both groups. An age-associated reduction of
factor structure was observed from adults to oldest old in the healthy group
(explained variance 60.4% vs 50.3%) and from adults to old in the T2DM group
(explained variance 57.4% vs 44.2%). Centenarians showed three-factor structure
similar to those of adults (explained variance 58.4%). The inflammatory component
became the major factor in old group and was the first one in T2DM. SEM analysis
in healthy subjects suggested that the glucose levels had an important role in
the oldest old. Factorial structure change during healthy ageing was associated
with a decrease in complexity but showed an increase in variability and
inflammation. Structural relationship changes observed in healthy subjects
appeared earlier in diabetic patients and later in centenarians