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/m2), 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 (r2 = 0.77, p < 0.05) but not in healthy subjects (r2 = 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.