Inclusion Criteria:  Age ≥30 and ≤80 years, BMI <40 kg/m2, screened for prediabetes or diabetes, and with enough plasma collected for β-amyloid 40 and 42 detection.  Exclusion Criteria:  History of diabetes mellitus and prediabetes, pharmacological treatment for hyperlipidaemia, any clinically systemic disease, any acute illness, chronic inflammatory disease or any infective disease.