The relationship between insulin resistance and cardiovascular risk factors in overweight/obese non-diabetic Asian adults: the 1992 Singapore National Health Survey.
OBJECTIVE
Insulin resistance (IR) is associated with cardiovascular risk factors including hypertension, dyslipidemia, glucose intolerance and hyperuricemia. The relationship between IR and these cardiovascular risk factors in obese non-diabetic individuals is not well studied. We explore this relationship by comparing the cardiovascular risk factors among insulin-sensitive and insulin-resistant overweight/obese non-diabetic Asian adults in the 1992 National Health Survey of Singapore.


METHODS
A total of 3568 subjects were examined in the survey, which involved a combination of disproportionate stratified sampling and systematic sampling. Anthropometric measurements, level of physical activity, blood pressure, insulin, lipid profile, uric acid and standard 75 g oral glucose tolerance test were performed after a 10 h overnight fast. Subjects with diabetes were excluded from the analysis. Homeostasis model assessment (HOMA) was used to assess insulin sensitivity. Relative LDL size was derived from the formula LDL/ApoB. We defined insulin-sensitive individuals as having a HOMA value <1.479 (below median in individuals without diabetes; n=3226) and overweight/obesity as body mass index (BMI) >or=25.0 kg/m(2).


RESULTS
There were 156 insulin-sensitive (S) and 679 insulin-resistant (R) overweight/obese individuals, respectively. The groups did not differ in terms of gender and ethnic distribution and level of physical activity. However, subjects in group S were younger than those in group R (mean+/-s.d.; 40.1+/-12.1 vs 42.4+/-12.7 y; P<0.05). Group R individuals were also slightly more obese globally and centrally than group S (BMI=28.2+/-3.2 vs 27.1+/-2.8 kg/m(2); waist circumference (WC)=86.7+/-9.3 vs 82.5+/-8.3 cm; P<0.01). There were more subjects with impaired glucose tolerance (IGT) in group R than in group S (29.7 vs 16.0%; P<0.01). After adjustment for age and indices of global and regional obesity (ie BMI and WC), insulin-resistant individuals showed higher apolipoprotein B, triglyceride, fasting (FPG) and 2 h post-load plasma glucose (2hPG) but lower HDL and LDL size. Further adjustment for FPG, 2hPG and level of physical activity had minimal impact on the results.


CONCLUSIONS
Insulin-resistant overweight/obese non-diabetic Asian adults had greater burden of the cardiovascular dysmetabolic syndrome than insulin-sensitive overweight/obese individuals. This could not be fully explained by differences in global and regional obesity, glucose tolerance and level of physical activity.
Lim
S-C
SC
Department of Endocrinology, Singapore General Hospital, Outram Road, Singapore. su_chi_lim@alexhosp.com.sg
Tan
B-Y
BY
Chew
S-K
SK
Tan
C-E
CE
D000328:Adult; D000368:Aged; D001208:Asia / Q000208:ethnology; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000208:ethnology / Q000209:etiology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000208:ethnology; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology