The purpose of this study is to assess safety and tolerability of AZD1656 after multiple repeated oral doses in patients with type 2 diabetes on top of insulin.

Inclusion Criteria:

• Female with non child-bearing potential
• Diagnosed Diabetes Mellitus patients treated with insulin alone or insulin in combination with other anti-diabetic drugs. Stable blood sugar control indicated by no changed treatment within 3 months prior to study start.
• HbA1c below or equal to 11 % at screening (HbA1c value according to international DCCT standard)

Exclusion Criteria:

• Clinically significant illness or clinically relevant trauma, as judged by the investigator, within two weeks before the first administration of the IP
• History of ischemic heart disease, stroke, transitorisk ischemic attack or symptomatic peripheral vascular disease
• Clinically significant abnormalities in clinical chemistry, hematology, or urinalysis results.