Sex differences in insulin resistance and cardiovascular disease risk.
BACKGROUND
The possibility that differences in insulin sensitivity explain why women, especially younger women, have a lower cardiovascular disease (CVD) risk than men remains an unsettled issue.


OBJECTIVE
The objective of this study was to evaluate whether sex disparities in CVD risk are associated with differences in insulin resistance.


METHODS
This was a cross-sectional study of women (n = 468) and men (n = 354) who had the measurement of CVD risk factors and steady-state plasma glucose (SSPG) concentration (insulin resistance) using the insulin suppression test. The population was also divided by median age (51 y) to evaluate the effect of age on sex differences.


RESULTS
In general, the SSPG concentration was similar between sexes. At higher BMI (≥30 kg/m(2)), women had significantly lower SSPG concentration than men (sex × BMI interaction, P = .001). However, sex differences in CVD risk factors were not due to differences in SSPG but accentuated by a higher degree of insulin resistance in younger (age < 51 y) but not older (≥ 51 y) individuals. In younger individuals, women had significantly (P ≤ .007) lower diastolic blood pressure and fasting glucose and triglyceride concentration compared with men in SSPG tertile 3 (most insulin resistant) but not in tertile 1 (least insulin resistant). Older women had lower diastolic blood pressure compared with men, regardless of SSPG. High-density lipoprotein cholesterol remained higher in women, regardless of age or SSPG.


CONCLUSIONS
The female advantage is not due to a difference in insulin action but results from an attenuation of the relationship between insulin resistance and CVD risk, especially in younger individuals.
MD, MS, Stanford University Medical Center, 300 Pasteur Drive, Room S025, Stanford, California 94305-5103. sunhkim@stanford.edu.
Sun H
SH
Kim
Gerald
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Reaven
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012727:Sex Characteristics; D017678:Sex Distribution; D055815:Young Adult
D001786:Blood Glucose; D008055:Lipids