Insulin resistance and tissue glycogen content in the tumor-bearing state

BACKGROUND/AIMS: Insulin resistance in cancer patients may play an importan t role in post-operative outcomes. METHODOLOGY: In an effort to understand the mechanism responsible, we measu red glucose uptake by euglycemic hyperinsulinemic glucose clamp, glycogen c ontent in skeletal muscle, liver, and adipose tissue by an enzymatic method , and facilitative glucose transporter mRNA by reverse transcription polyme rase chain reaction (RT-PCR), in 10 patients with gastrointestinal cancers. Glucose uptake was also examined in 5 volunteers. RESULTS: The M value was significantly smaller in cancer patients (6.11+/-2 .49mg/kg/min) than in controls (8.55+/-0.91mg/kg/min). A significant decrea se in glucose storage was also observed in cancer patients compared with th at of controls, 3.18+/-2.46 and 4.95+/-0.55mg/kg/min, respectively. The gly cogen content of skeletal muscle from cancer patients averaged 12.1+/-2.7 m u g/mg tissue and was correlated with the M value (r=0.75, p<0.05.). Muscle glycogen had an even stronger correlation to glucose storage (r=0.964, p<0 .05). The glycogen content of liver averaged 105.4+/-79.0 mu g/mg tissue bu t was not related to the M value. Glycogen in adipose tissue was not measur able by this method. Muscle and liver samples were positive for periodic an d Schiff (PAS) stain, while the stain in adipose tissue was very weak. Gluc ose transporter 4 mRNA was the dominant facilitative glucose transporter in skeletal muscle. CONCLUSIONS: These results suggest that patients with gastrointestinal (GI) cancer and insulin resistance have decreased glycogen storage in skeletal muscle. These may be the patients who are in need of pre-operative nutritio nal support.