['type 1 diabetes mellitus']
['ipragliflozin', 'placebo']

        Inclusion Criteria:

          -  The subject has been diagnosed with type 1 diabetes mellitus

          -  The subject has been receiving insulin therapy for the treatment of diabetes mellitus.

          -  The subject has not switched from an insulin product to another insulin product or
             switched between continuous subcutaneous insulin infusion (CSII) and multiple daily
             injections (MDI).

          -  The subject has an HbA1c value between 7.5% and 11.0% and the difference of HbA1c
             value is within ± 2.0%.

          -  The subject has a fasting blood C-peptide level < 0.6 ng/mL.

          -  The subject has a body mass index (BMI) between 20.0 kg/m2 and 35.0 kg/m2.

        Exclusion Criteria:

          -  The subject has type 2 diabetes mellitus.

          -  The subject has participated in a clinical study or post marketing study of another
             drug or medical equipment within 12 weeks (84 days) before providing written informed
             consent, or is currently participating in such a study.

          -  The subject has received treatment with ASP1941 (ipragliflozin) or participated in a
             clinical study of ASP1941 (excluding subjects who discontinued before the
             investigational period).

          -  The subject participated in this study previously.

          -  The subject has received a hypoglycemic agent other than insulin or an α-glucosidase
             inhibitor.

          -  The subject has proliferative retinopathy (except for those who have undergone
             photocoagulation etc. and whose symptoms are stable).

          -  The subject has experienced severe hypoglycemia.

          -  The subject has experienced diabetic ketoacidosis.

          -  The subject has chronic disease that requires the continuous use of corticosteroids,
             immunosuppressants, etc.

          -  The subject has symptomatic urinary tract infection or symptomatic genital infection.

          -  The subject has a history of recurrent urinary tract infection or recurrent genital
             infection.

          -  The subject has a history of cerebral vascular attack, unstable angina, myocardial
             infarction, vascular intervention, or another serious heart disease.

          -  The subject has a concomitant malignant tumor or a history of malignant tumor

          -  The subject has a history of an allergy to ASP1941 (ipragliflozin) and/or similar
             drugs (drugs possessing SGLT2 inhibitory action).

          -  The subject has psychiatric disorder that is inappropriate for participation in the
             study.

          -  The subject has drug addiction or alcohol abuse.

          -  The subject has severe infection or serious trauma, or is perioperative.

          -  The subject has a history of medically significant renal disease such as renovascular
             occlusive disease, nephrectomy and/or renal transplant.

          -  The subject has any symptoms of dysuria, anuria, oliguria, or urinary retention.

          -  The subject has severe renal impairment or end-stage renal failure requiring dialysis.

          -  The subject has an Aspartate Aminotransferase and/or Alanine Aminotransferase value
             that exceeds 2 times, or a total bilirubin value that exceeds 1.5 times the upper
             limit of the reference range.

          -  The subject has uncontrolled severe hypertension.

          -  The subject has serious gastrointestinal disease or a history of operation for serious
             gastrointestinal disease.
      