The validity of serum squalene and non-cholesterol sterols as surrogate markers of cholesterol synthesis and absorption in type 2 diabetes.
OBJECTIVE
Serum non-cholesterol sterol ratios to cholesterol reflect cholesterol metabolism in non-diabetes populations. In type 2 diabetes (T2D) cholesterol metabolism is perturbed, and the role of squalene and non-cholesterol sterols has not been related to absolute cholesterol metabolism in detail.


OBJECTIVE
We analyzed absolute cholesterol synthesis, absorption % of dietary cholesterol, and serum squalene and non-cholesterol sterol ratios (measured with gas-liquid chromatography) in 64 T2D subjects (age 41-74 years, BMI 21-40 kg/m(2)).


RESULTS
Serum precursors of cholesterol were related to cholesterol synthesis (e.g. serum squalene to cholesterol ratio vs absolute synthesis r=0.493, p<0.001), and serum cholestanol and plant sterol ratios were related to absorption % (e.g. cholestanol vs absorption %, r=0.455, p<0.001). Furthermore, the proportions of serum synthesis/absorption markers were correlated with variables of absolute cholesterol metabolism (e.g. squalene/sitosterol vs absolute synthesis/absorption %, r=0.569, p<0.001). Serum synthesis and absorption markers (lathosterol vs cholestanol, r=-0.545, r<0.001) and absolute synthesis and absorption (r=-0.540, p<0.001) were interrelated suggesting intact regulation of cholesterol metabolism in the whole study population. Absolute synthesis/absorption ratio indicated that a change of dietary cholesterol absorption by 1% changed the mean cholesterol synthesis by 27 mg/d to the opposite direction.


CONCLUSIONS
In T2D including varying body weight and altered cholesterol metabolism, serum non-cholesterol sterols and squalene reveal reliable information of cholesterol synthesis and absorption without complicated clinical and laboratory methods.
Simonen
Piia
P
Department of Medicine, Division of Internal Medicine, University of Helsinki, Helsinki, Finland.
Gylling
Helena
H
Miettinen
Tatu A
TA
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D002849:Chromatography, Gas; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010840:Phytosterols / Q000097:blood*; D013185:Squalene / Q000097:blood*
D015415:Biomarkers; D010840:Phytosterols; D013185:Squalene; D002784:Cholesterol