Although glycemic control has an important impact on the clinical outcomes of patients with diabetes undergoing dialysis, there is a paucity of data on the relationship between glucose metabolism and clinical parameters in these patients. In this study, we compared a cohort of 48 patients with type II diabetes undergoing continuous ambulatory peritoneal dialysis (CAPD) with 84 age- and sex-matched patients with type II diabetes with similar disease duration but normal renal function. Compared with those with normal renal function, patients with type 2 diabetes undergoing CAPD had greater serum angiotensin-converting enzyme activity (median, 57.4 U/L; range, 33.5 to 100.0 U/L v 46.9 U/L; range, 11.6 to 111.2 U/L; P < 0.005), fasting C-peptide (median, 9.1 ng/mL; range, 0.9 to 30.0 ng/mL v 2.2 ng/mL; range, 0.2 to 20.3 ng/mL; P < 0.0001) and triglyceride levels, and lower serum albumin concentrations. Among the patients undergoing CAPD, there was a preponderance of men in the insulin-treated group. Insulin-treated patients also had greater plasma albumin levels and body weights and lower fasting serum C-peptide levels (2.81 +/- 1.77 v 3.12 +/- 2.04 ng/mL; analysis of variance, P = 0.007 adjusted for fasting glucose concentration). Multivariate analysis showed duration of diabetes, hemoglobin A(1c) (HbA(1c)) level, and body weight were independent determinants of insulin requirement in patients undergoing CAPD. The daily insulin dosage required was related to the duration of diabetes (r = 0.5; P = 0.007). In summary, among patients with end-stage renal failure, insulin-treated patients had greater body weights and plasma albumin levels but lower cholesterol levels. Plasma C-peptide concentration and duration of diabetes were the main determinants of insulin requirement, reflecting a decrease in beta-cell reserve, whereas the daily insulin dose correlated mainly with body weight, HbA(1c) level, and duration of diabetes. Kt/V had no effect on insulin resistance or insulin requirement of the patients.