N-epsilon-(carboxymethyl)lysine levels in patients with type 2 diabetes: Role of renal function

Advanced glycation end products (AGEs) such as N-epsilon-(carboxymethyl)lys ine (CML) have been implicated in the development and progression of diabet ic nephropathy. The aim of the present study is to investigate AGE levels i n patients with type 2 diabetes with special regard to the role of renal im pairment. Serum and urine CML levels (using a newly developed enzyme-linked immunosorbent assay), as well as serum AGE-fluorescence, were measured in 109 patients with type 2 diabetes. Patients were divided into groups with n ormal and impaired renal function. We found elevated serum fluorescent AGE and CML levels, as well as decreased urinary CML excretion rates, in patien ts with diabetes with renal impairment, but not those with normal renal fun ction. In the presence of impaired renal function, serum CML and fluorescen t AGE levels showed a significant inverse relation with creatinine clearanc e and a significant direct correlation with each other. No relationship cou ld be found between serum AGE levels and parameters of blood glucose contro l or the presence of the following clinical complications: ischemic heart d isease, diabetic retinopathy, and neuropathy. We conclude that the decline in renal function leads to increased serum AGE levels in patients with type 2 diabetes. (C) 2001 by the National Kidney Foundation, Inc.