A 2-week , dose-ranging , randomized , double-blind , placebo-controlled proof-of-concept study randomly assigned 70 adults with type 1 diabetes ( HbA1c 7-10 % ) , who were receiving treatment with stable doses of insulin , to one of four dapagliflozin doses ( 1 , 2.5 , 5 , or 10 mg ) or placebo .