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.