Implications of body fat distribution in an older twin population

Background. As people age, far becomes preferentially deposited in the abdo minal region over the periphery, and such changes are thought to be associa ted with adverse metabolic outcomes. We were interested in whether body mas s index (BMI) and waist-hip ratio (WHR) are differentially associated with fasting insulin levels, triglycerides, and blood pressure (systolic and dia stolic) in an older population. We were also interested in whether these as sociations change after controlling for genetic influences. Methods. Data were obtained as part of the Swedish Adoption/Twin Study of A ging. All blood samples and anthropometric measures were assessed from 1989 -1991 except insulin, which was assessed from 1986-1988. The sample contain s 263 twin pairs (97 monozygotic and 166 dizygotic), 56% women, average age 65 years. Results. In men and women, WHR and BMI were significantly associated with a ll the metabolic variables except for diastolic blood pressure. When BMI's association with the metabolic variables was assessed independent of WHR, i t remained significantly associated with all metabolic variables except dia stolic blood pressure in men and triglycerides in women. When WHR's associa tion with the metabolic variables was assessed independent of BMI, it did n ot remain significantly associated with any of the metabolic variables in m en and remained significantly associated with insulin and diastolic pressur e in women. After controlling for genetic effects, the relationship between WHR and the metabolic variables became nonsignificant. However, BMI remain ed significantly associated with systolic blood pressure and triglycerides in men, independent of WHR. Conclusion. The results suggest that overall body fat is important to consi der in relation to these metabolic parameters in older individuals. The res ults also suggest that BMI may share associations with blood pressure and t riglycerides beyond those that can be attributed to familial influences.