Lower-body fat mass as an independent marker of insulin sensitivity - the role of adiponectin

AIMS: To study the association between lower-body fat and estimates of whole-body insulin sensitivity in middle-aged men with and without a history of juvenile onset obesity, and to determine the possible mediating role of fasting serum adiponectin level as an insulin-sensitizing peptide. METHODS: A total of 401 men aged 39 - 65 y, body mass index 18 - 54 kg/m(2), participated in the study. The following variables were measured on the study participants: regional body fat distribution as assessed by dual energy X-ray absorptiometry, abdominal sagittal diameter, maximal oxygen uptake (VO(2)max), physical activity, fasting and post-glucose load levels of plasma glucose, serum insulin, and blood non-esterified fatty acid plus fasting levels of serum adiponectin and HbA1c. RESULTS: Lower-body fat mass was positively associated with insulin sensitivity as estimated by Matsudas index also after adjusting for age, lean tissue mass, trunkal fat mass, weight changes since draft board examination, VO(2)max and the level of physical activity. In a subgroup of men selected for a large lower-body fat mass, fasting serum insulin concentration was 24% lower (P < 0.01) and fasting serum adiponectin 33% higher (P < 0.005) compared to a subgroup of men with a small lower-body fat mass but with similar trunkal fat mass. CONCLUSION: Lower-body fat mass is positively associated with an estimate of insulin sensitivity independently of trunkal fat mass in both lean and obese middle-aged men and this effect could partly be statistically explained by variations in serum adiponectin levels. International Journal of Obesity (2005).