Effect of Systemic Hyperinsulinemia in Cancer Patients1

Data defining the isolated effect of insulin on whole body protein and glucose metabolism in cancer patients are limited. Ten normal volun teers (controls), age 55 ±3 years (mean ±SEM); 8 cancer patients, age 61 ±3years, weight loss 2 ±1% (CANWL); and 8 cancer patients, age 55 ±2 years, weight loss 18 ±2% (CAWL), were studied in the postabsorptive state. Whole body leucine kinetics were determined during a baseline and then a study period during which insulin was infused at 1.0 milliunits/kg/min to achieve a high physiological level of 71 ±6, 83 ± 5, and 64 ±5 microunits/ml in controls, CANWL, and CAWL, respec tively. Whole body net balance equals protein synthesis minus protein breakdown. Glucose disposal (mg/kg/min) is the rate of D30 infusion at steady state. Glucose disposal of CANWL and CAWL during the study period was significantly (P < 0.05, analysis of variance) less than controls (3.91 ± 0.6 in CANWL, 3.66 ±1.0 in CAWL, and 5.87 ±0.6 mg/kg/min in controls), suggesting resistance to insulin with respect to carbohydrate metabolism. Hyperinsulinemia, under euglycemic and near basal amino acid conditions, significantly reversed the negative postabsorptive leucine net balance (P < 0.05, analysis of variance) by decreasing protein breakdown in controls as well as weight-stable and weight-losing cancer patients, suggesting that cancer patients are not resistant to the anticatabolic effect of insulin with respect to whole body protein metabo lism.