Factor analysis of the metabolic syndrome: obesity vs insulin resistance as the central abnormality.
OBJECTIVE
To evaluate whether there is one central abnormality contributing to the conditions associated with the metabolic syndrome (MES), or whether one abnormality is contributing on multiple levels.


METHODS
We recruited 145 Chinese subjects aged 17-68 y with varying degrees of insulin-sensitivity (IS): 33 healthy, 59 with type 2 diabetes mellitus, 32 essential hypertensives and 21 dyslipidaemics. IS was evaluated by the short insulin sensitivity test using a 0.1 U/kg intravenous bolus dose of insulin. Blood pressure, anthropometric measures and biochemical parameters associated with IS were also measured. Exploratory factor analyses (EFA) were performed in the entire group of 145 subjects and in the 76 with normal glucose tolerance.


RESULTS
EFA in all 145 subjects defined three distinct, independent factors. Factor 1 was interpreted as general and central adiposity, impaired IS and glucose intolerance, Factor 2 was associated with hypertension and general and central obesity, whilst Factor 3 was strongly related to low HDL-cholesterol and high triglyceride concentrations and weakly to waist circumference. In patients with impaired glucose tolerance, only two factors were identified; factor 1 related to reduced IS, impaired glucose tolerance, dyslipidaemia and general and central adiposity, and factor 2 which was related to blood pressure and general and central adiposity.


CONCLUSIONS
These models suggest that the clustering of variables in MES is a result of multiple factors linked by adiposity and not a single aetiology. Furthermore, increases in blood pressure are related to obesity in these Chinese subjects rather than decreased IS per se.
Anderson
P J
PJ
Division of Clinical Pharmacology, The Department of Medicine and Therapeutics, The Chinese University of Hong Kong, The Prince of Wales Hospital, New Territories, Hong Kong SAR. panderson@hrc.govt.nz
Critchley
J A
JA
Chan
J C
JC
Cockram
C S
CS
Lee
Z S
ZS
Thomas
G N
GN
Tomlinson
B
B
D000005:Abdomen; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D001824:Body Constitution; D002681:China; D005163:Factor Analysis, Statistical; D005260:Female; D018149:Glucose Intolerance; D006801:Humans; D006973:Hypertension / Q000150:complications*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D024821:Metabolic Syndrome / Q000502:physiology*; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D014280:Triglycerides / Q000097:blood
D014280:Triglycerides