Glucose tolerance in relation to skeletal muscle enzyme activities in cancer patients

Abstract

Glucose metabolism and skeletal muscle enzyme activities were studied in nineteen cancer patients and twelve matched controls. The fasting insulin values were normal but the fasting glucose values and the sum of glucose were increased and the sum of insulin was decreased during intravenous glucose tolerance test in the cancer patients. The elimination rate of glucose (k-value) during glucose challenge was, however, not significantly different in cancer patients as compared with that of appropriate controls. The activities of enzymes representative for glycogen turnover, glycolysis, citric acid cycle and respiratory chain were significantly lower in the muscle tissue of cancer patients, while the activity of 3-hydroxyacyl-CoA dehydrogenase, an enzyme in the β-oxidation of fatty acids, was unchanged and the activity of glucose-6-phosphate dehydrogenase was significantly higher. Rate limiting enzyme activities in muscle tissue, phosphofructo-kinase and cytochrome c oxidase correlated significantly with plasma insulin and glucose during glucose challenge. The results point at the possibility of covariat-ing debilitation of pancreatic beta-cells and skeletal muscle enzymes caused by the malignant tumour.

Key Words:

• cancer
• glucose tolerance
• skeletal muscle enzymes