Fasting insulin modifies the relation between age and renal function

Background. The worldwide increase in end-stage renal disease has been alleged to be associated with insulin resistance-related conditions. Insulin resistance and the concomitant compensatory hyperinsulinaemia may accelerate age-related decline in renal function through inducing glomerular hyperfiltration, even in nondiabetic subjects. This population-based study is the first to investigate whether fasting insulin concentrations modify the relationship between age and renal function in a general non-diabetic population. Methods. Fasting insulin was measured in 3432 subjects, representing the general population. Cross-sectional analyses of the association between age, renal function and its modification by insulin were performed by means of linear regression. Renal function was assessed as 24-h creatinine clearance (CrCl) and 24-h urinary albumine excretion (UAE). Results. Age was 48 +/- 12 (range: 28-75) years, 44% were male, CrCl was 100 +/- 26ml/min and UAE was 7.0 (5.4-10.7) mg/24 h. The results confirmed a parabolic relation between age and renal function. Fasting insulin modified these parabolic relationships of age with CrCl and UAE (P