Insulin-mediated vasodilation and glucose uptake are independently related to fasting serum nonesterified fatty acids in elderly men

Objectives. To investigate candidate predictors for insulin sensitivity in healthy elderly males, with special reference to the influence of insulin-mediated skeletal muscle blood flow and serum nonesterified fatty acids (NEFA). Subjects. From the participants in a health survey of 70-year-old males, focusing on cardiovascular risk factors, a subgroup of 46 men was sampled. Only men who declared themselves healthy and without medication were included. Interventions. Insulin sensitivity was measured with the euglycaemic hyperinsulinaemic clamp. Leg blood flow was measured before and during the clamp, using the Doppler ultrasound technique. Results. Hyperinsulinaemia [steady-state plasma insulin 105(15) mU L-1] increased leg blood flow by 10% (P < 0.004). When tested in bivariate analysis incremental leg blood flow was only significantly related to the serum NEFA concentration (r = -0.38, P < 0.01) amongst a number of measured variables. Insulin-mediated glucose disposal was related to body mass index (BMI) (r = 0.49, P = 0.0006), waist/hip ratio (r = -0.31, P = 0.036), NEFA (r = - 0.50, P = 0.0004) and heart rate (r = -0.34, P = 0.02). In multivariate analysis only BMI and NEFA remained significantly related to whole-body glucose uptake. Conclusions. The study demonstrates that in elderly men BMI and fasting serum NEFA but not insulin-induced vasodilation are related to insulin sensitivity. High fasting levels of NEFA relate to both impaired insulin-mediated vasodilation and impaired glucose disposal, respectively. These two insulin actions were not interrelated, however, a finding which may indicate dissociated mechanisms.