Background: Our objective was to investigate the relationship between abdominal obesity (AO), as measured by waist circumference (WC), insulin resistance (IR), and components of the metabolic syndrome (MS).
Methods: A cross-sectional study was carried out with 283 subjects (130 males and 153 females aged 25-65 years) from a primary care outpatient clinic in Valencia (Spain) over a period of 1 year. Body mass index (BMI), waist circumference (WC), blood pressure (BP), total cholesterol, triglycerides, HDL-C, glucose, and insulin were measured by standard methods. IR was defined as HOMA-IR equal to or greater than 3.8.
Results: The prevalence of IR was 39.6%. Subjects were divided into groups according to WC. A 'normal' WC was defined as below 88 cm in women and below 102 cm in men; 'AO' was defined as a WC equal to or above 88 cm in women and equal to or above 102 cm in men. The prevalence of IR was 31.7% in the group with normal WC and 54.6% in the AO group (P<0.001). The percentage of subjects with the MS (high BP, dyslipemia or abnormal glucose tolerance) significantly increased (P<0.001) in subjects with AO (48.4 vs. 18.8% in normal WC subjects). AO is an indicator of IR with an odds ratio of 2.59 (95% CI 1.55-4.29).
Conclusions: AO, expressed as WC, appears to be a good indicator of risk for IR and the MS, particularly in non-obese subjects (BMI<30). The main independent parameters of risk for IR are WC and TG, whereas those for the MS are IR, WC, and age.