Serum advanced glycosylation end-products in patients on hemodialysis and CAPD

Abstract

Objectives: Part I: To evaluate the long-term effects of daily glucose absorption from the peritoneal dialysis fluid on the formation of low-molecular-weight advanced glycosylation end-products (AGE-peptides) in nondiabetic continuous ambulatory peritoneal dialysis (CAPD) patients. Part II: To determine the acute effect of CAPD on serum AGE-peptide concentrations.

Design: Part I: Noninterventional, parallel, cross-sectional clinical trial. Part II: Crossover clinical trial.

Setting: A university-based hospital, and clinics.

Patients: Part I: Sixty nondiabetic subjects recruited into three age-matched (+/- 5 years) groups, as follows: 20 healthy volunteers (controls); 20 hemodialysis patients; and 20 CAPD patients. Part II: Eight patients with diabetes mellitus (type I or II) and chronic renal failure who were about to undergo CAPD.

Intervention: Part I: None. Part II: Uninterrupted CAPD, as medically required.

Measurements: Part I: To determine serum AGE-peptide concentrations blood samples were obtained randomly from controls and CAPD patients, and predialysis from hemodialysis patients. Hemoglobin A1c was also measured in all subjects. Part II: To determine serum AGE-peptide concentrations, blood samples were collected within one month prior to initiation of CAPD (predialysis) and, again, one week after initiation of uninterrupted CAPD (postdialysis). Hemoglobin A1c was measured predialysis.

Results: Part I: Mean hemoglobin A1c values for all groups were within the normal range; however, the mean value for CAPD patients was significantly higher than for both hemodialysis patients and healthy controls (controls, 5.21% +/- 0.6%; hemodialysis, 5.12% +/- 0.5%; CAPD, 5.78% +/- 0.6%; p < 0.01). The dialysis patients had a significantly higher mean serum AGE-peptide concentration than the control subjects (controls, 7.02 +/- 3.4 units/mL; hemodialysis, 11.9 +/- 3.6 units/mL; CAPD, 11.1 +/- 4.5 units/mL; p < 0.01). There was no difference in the mean serum AGE-peptide concentration of patients in the hemodialysis and CAPD groups. Part II: The mean hemoglobin A1c value in the diabetic predialysis patients was 9.2% +/- 1.9%. There was no difference between the predialysis and postdialysis serum AGE-peptide concentrations (predialysis, 16.9 +/- 9.6 units/mL; postdialysis, 16.0 +/- 2.9 units/mL; p = 0.78).

Conclusions: Despite the increased glucose load and the higher hemoglobin A1c values, indicating poor glycemic control, nondiabetic CAPD patients did not have higher serum AGE-peptide concentrations than the nondiabetic hemodialysis patients. In diabetic patients, CAPD did not further increase the serum concentrations of AGE-peptides.