The relationship of waist circumference to blood pressure: the Olivetti Heart Study

BACKGROUND: The association between overweight, high blood pressure (BP),
and insulin resistance is well established, but the role of body fat
distribution in this association has yet to be fully elucidated. The aim
of this study was to investigate the role of central adiposity in the
association between overweight, high BP, and insulin resistance.
METHODS: A total of 1,079 men participated in the follow-up of the Olivetti
Heart Study from 1994 to 1995. The present analysis includes 768 men, after
the exclusion of 184 participants on pharmacological treatment for
hypertension. In 65 men fasting blood glucose was >7 mmol/L; in 48, age
was below or above 2 standard deviations from the mean of the population;
and in 14 the data set was incomplete. Anthropometric indices
of adiposity, metabolic variables (including fasting serum insulin and
homeostasis model assessment HOMA] index of insulin sensitivity), and BP
were measured. RESULTS: In univariate analysis, waist circumference was the
anthropometric index that best correlated with BP (P < .001). In multiple
regression analysis, waist circumference remained the strongest independent
predictor of BP after adjustment for confounders. Significant increase of
systolic (P value for trend analysis < .001) and diastolic (P < .001)
pressure, heart rate (P = .003), fasting and postload serum insulin (P <
.001), and HOMA index of insulin sensitivity (P <.001) were observed across
age-adjusted quintiles of waist circumference. Greater degrees of central
adiposity were associated with higher prevalence of elevated
BP values and insulin resistance (P value < .001, chi2 for linear trend).
CONCLUSIONS: In middle-aged men, a central distribution of body fat is
associated with increased BP,independently of body mass index and insulin
resistance, thus suggesting a keyrole of central adiposity in the full
expression of the "metabolic syndrome."