This study is intended to prospectively research the treatment reality and long-term disease control of Type 2 Diabetes Mellitus (T2DM) patients who are initiating 2nd line anti-diabetes treatment in sites across Japan.

This study is a single country, multicenter, observational, prospective, longitudinal cohort study which will include adult patients with documented history of T2DM who are initiating a second line oral or parenteral anti-diabetes mediation after their first line anti-diabetic therapy in real world setting. The follow-up period is 3 years. Patients will undergo clinical assessments and receive standard medical care as determined by the treating physician. Patients will not receive experimental intervention or experimental treatment as a consequence of their participation in the study.

Inclusion Criteria:

1. Written consent obtained
2. Aged > = 20 years
3. Diagnosed with type 2 diabetes mellitus
4. Initiating a second oral or parenteral anti-diabetic therapy added to oral anti-diabetic monotherapy or switching from the monotherapy to another monotherapy with different drug class

Exclusion Criteria:

1. Diagnosis of Type 1 Diabetes Mellitus
2. Current pregnancy
3. Current treatment for any cancer
4. Current dialysis treatment or renal transplantation
5. Current treatment with any oral steroids
6. Participation in any randomized control trials
7. Presence of any condition/circumstance which in the opinion of the investigator could significantly limit the complete follow up of the patient (e.g. tourist, non-native speaker who does not understand the local language where interpreter are not available, psychiatric disturbances, alcohol or drug abuse).

Adult patients with documented history of type 2 diabetes mellitus who are initiating their second line oral or parenteral anti-diabetics medication after first line oral diabetic therapy