1. In eight clinically stable symptomatic human-immunodeficiency-virus-infected patients and in seven healthy control subjects,
glucose and fat metabolism were studied, using indirect calorimetry and primed continuous infusions of [3-3H]
glucose and [14C]
palmitate. 2. Studies were performed in the post-absorptive state (16 h of overnight fasting) and again after 22 h of overnight fasting. 3. In the post-absorptive state, net fat oxidation and
triacylglycerol ('
triglyceride') concentrations were significantly higher in the patients, but concentrations and turnover of
free fatty acids were not significantly different between patients and control subjects. After 22 h of overnight fasting,
free fatty acid turnover in the patients rose to significantly higher levels when compared with the control subjects. 4. Post-absorptive
glucose oxidation,
glucose turnover and
glucose clearance did not differ between patients and control subjects. Although fasting induced a significantly greater decline in
glucose turnover in the patients, plasma
glucose concentrations decreased comparably in patients and control subjects. 5. No differences were found in plasma concentrations of
insulin or of the counter-regulatory
hormones between patients and control subjects. 6. It is concluded that the metabolic adaptation to short-term
starvation in clinically stable human-immuno-deficiency-virus-infected patients differs from that in healthy control subjects. Short-term
starvation results in a significantly greater fall in
glucose turnover, whereas fat metabolism is clearly stimulated. These alterations cannot be explained by differences in the concentrations of
insulin or of the counter-regulatory
hormones.