Effects of oral glucose on intermediary metabolism in continuous ambulatory peritoneal dialysis patients versus healthy subjects

Objective:To explore the mechanisms and metabolic consequences of the insulin resistance of patients treated by continuous ambulatory peritoneal dialysis (CAPD). Design: CAPD patients and healthy subjects ingested a similar mean oral glucose load per kilogram of fat-free mass (FFM) [1.20 +/- 0.03 g/(kg FFM) vs 1.20 +/- 0.06 g/(kg FFM); CAPD vs healthy subjects]. Substrate oxidation was monitored over 6 hours using indirect calorimetry. Setting: Peritoneal dialysis unit of a tertiary-care institutional center. Outcome Measures: Glycemia, insulinemia, substrate oxidation. Patients: Six CAPD patients (68 +/- 5 yr) and 6 healthy subjects (24 +/- 1 yr). The CAPD patients had similar body mass index (21.4 +/- 1.3 vs 22.9 +/- 1.1 kg/m(2)), a higher percent fat (25.8% +/- 3.7% vs 16% +/- 2.2%; p < 0.05), and a lower FFM (42.2 +/- 2.2 kg vs 56.5 +/- 2.6 kg; p < 0.01) than healthy subjects. Results: The CAPD patients displayed a higher glycemic and insulinemic responses to glucose than did healthy subjects (p < 0.05), but similar glucose oxidation and storage. Lipid oxidation and plasma nonesterified fatty acids were not increased in CAPD patients versus healthy subjects, in spite of a higher adiposity. Fat oxidation was related to fat mass in CAPD patients (r(2) = 0.77, p < 0.05) but not in healthy subjects (r(2) = 0.05). Conclusion: CAPD patients display an insulin-resistance not explained by an increased lipid oxidation. The maintenance of intracellular glucose utilization at the expense of higher glycemic and insulinemic responses suggests a defective glucose transport.