Insulin clearance closely resembles:

Inulin is a polysaccharide composed of fructose units. Inulin is filtered at the glomerulus of the kidney but is neither secreted nor reabsorbed by the tubule so it is used to measure the GFR. Estimation of GFR is used clinically to assess the severity and course of renal disease. Compounds used to measure GFR should have the following propeies: Ability to achieve a stable plasma concentration Freely filtered at the glomerulus Not reabsorbed, secreted, synthesized, or metabolized by the kidney. Ref: Topics in Clinical Nutrition By John A. Allocca page 37. Renal Pathophysiology: The Essentials By Helmut G. Rennke, M.D. page 23.