A method for treating Type II diabetes by administering to an affected individual a combination of chromic tripicolinate and biotin. The two compounds are administered orally or parenterally at in daily dosages which provide between 50 and 1,000 .mu.g of chromium and between 25 .mu.g and 200 mg biotin, the amounts of chromium and biotin being selected together to provide a greater than additive effect.