The purpose of this study is to investigate patient's usability, preference and blood glucose control for the new prefilled disposable insulin lispro mixture (Humalog Mix 25 injection KwikPen®). For that purpose, randomized open-label, 2-period direct comparative crossover study is planned in comparison with insulin aspart mixture (Novo Rapid 30 Mix injection FlexPen®).

• Concomitant drugs The treatment with other insulin preparation is prohibited during the study period. As to the drugs except insulin that have been used for the treatment of diabetes and its complication since the time before the study, the content should not be changed during the study in principle unless the complication is cured. If any new complication occurs during the study period, an appropriate treatment is given by the judgment of investigator.

• Compliance with treatment method The investigator gives sufficient explanation on the following contents to the patient.

  • To inject the prescribed volume of insulin at the prescribed time.
  • To observe the appointed date for the next visit.

• Termination of assessment The study is discontinued if any of the following events occurs after the start of study.

  • Important protocol violation
  • When continued treatment is judged difficult due to the onset of an adverse event
  • Death
  • When the follow-up of patient becomes impossible
  • Other than the above, when the investigator judges it necessary to discontinue the study

Inclusion Criteria:

• Type 2 diabetes mellitus patients
• Patients who have used Humalog Mix 25 injection KwikPen® or Novo Rapid 30 Mix injection FlexPen® for 3 months or more.
• Outpatients regularly visiting hospital
• Patients 20 years old or older but under 80 years old (gender is disregarded)

Exclusion Criteria:

• Patients with a serious complication in the heart, liver or kidney
• Pregnant or possibly pregnant patients, or lactating patients
• Patients complicated with a malignant tumor at present.
• Patients allergic to insulin analog preparations.
• Patients taking an illegal drug.
• Patients participating in other clinical study.
• Other than the above, patients judged inappropriate as the subjects of this study by the investigator