Metabolic effects of the glucose tolerance factor (GTF) in normal and genetically diabetic mice

The acute metabolic effects of glucose tolerance factor (GTF), the biologically active form of trivalent chromium, were studied in normal and genetically diabetic (db/db) mice. A single intraperitoneal injection of GTF significantly reduced the nonfasting plasma glucose level in normal mice by 38 per cent, and in diabetic mice by 14 to 29 per cent. Time course studies in normal and diabetic mice showed a maximal lowering of plasma glucose at four hours after GTF treatment. Furthermore, a single injection of GTF significantly lowered the elevated plasma triglyceride and cholesterol levels by 47 and 35 per cent, respectively, four hours after injection. Genetically diabetic mice are refractory to insulin, and treatment with exogenous insulin produced a smaller decrement in plasma glucose (11-18 per cent). The combination treatment of diabetic mice with GTF and exogenous insulin was significantly more effective in reducing plasma glucose (39-51 per cent) and triglycerides (76 per cent) than either treatment alone. These findings are consistent with the suggestion that GTF and insulin act synergistically.