In vivo glycogen and lipid synthesis by various tissues from normal and metformin-treated KK mice.

The incorporation of [14C] U-glucose into glycogen by liver, kidney and skeletal muscle and that into total lipid by adipose tissue was studied in noninsulin-dependent genetically diabetic KK mice treated either with metformin (50 mg/kg) or water for 10 weeks. Results show that glycogen synthesis was increased in the skeletal muscle from metformin-treated mice. Liver and kidney glycogen synthesis was not affected by metformin. Glucose incorporation was significantly increased into lipid in metformin-treated mice. Insulin administration stimulated lipid synthesis in adipose tissue, but had no effect on muscle glycogen synthesis in metformin-treated mice. These data suggest that chronic metformin treatment potentiates the endogenous insulin action on glucose in skeletal muscle and adipose tissue, and thus confirm our previous results of increased glycogen synthesis by skeletal muscle in metformin-treated KK mice.