Effect of Renin-angiotensin-system Blockade on Urinary Free Light Chains in Patients With Type 2 Diabetes Mellitus

Free light chains (FLCs) are low-molecular-mass molecules (kappa and lambda light chains), which are by-products of normal immunoglobulin synthesis and are normally excreted through the kidneys. Presence of light chains in the urine is a marker of tubular dysfunction. In patients with impaired kidney function, serum concentrations and urinary excretion of polyclonal FLCs have been noted to be increased. Increased excretion of FLCs and other low-molecular weight proteins \[cystatin C, NGAL\] in the urine may contribute to progression of chronic kidney disease. Higher Cystatin C has been demonstrated to be related to development of albuminuria. Neutrophil gelatinase-associated lipcalin (NGAL) excretion in the urine is a marker of tubular injury in the kidney and has been shown to be elevated in subjects with type 1 and 2 diabetes mellitus (DM). Angiotensin-converting enzyme inhibitors (Ace Inh) and angiotensin II receptor blockers (ARB) class of drugs are renoprotective in nature and are the first line therapy for treatment of diabetic nephropathy. There is no longitudinal data evaluating the effect of Ace Inh and ARB class of drugs on urinary FLCs (UFLCs). Our hypothesis is that UFLCs are increased in patients with DM with and without kidney disease and that treatment with Ace Inh and/or ARB will decrease UFLCs in these patients. Additionally, we will explore the change in other low molecular weight proteins \[cystatin C, and NGAL\] in response to treatment with Ace Inh and ARB.