Postreceptor effect of metformin on insulin action in mice.

To investigate the possibility that metformin (dimethylbiguanide) modifies insulin-mediated glucose metabolism by an effect that is independent of insulin receptor binding, glycogenesis and insulin binding were measured in soleus muscles isolated from streptozocin diabetic mice after treatment with 60 mg kg-1 metformin daily for 10 weeks. This dose of metformin increased insulin-stimulated glycogenesis but did not affect insulin binding in the soleus muscles of streptozocin diabetic mice. The results suggest that metformin can influence postreceptor sites of insulin action independently of insulin receptor binding.