This study is a placebo-controlled study in patients with Type 2 Diabetes Mellitus to assess safety and tolerability parameters, the levels of GSK716155 in the bloodstream when it is given at the same dose 7 days apart, and the impact this medication has on various substances in the blood. Assessments include ECGs, vital signs, repeat blood sampling and monitoring of any side effects.

Inclusion criteria:

• Subjects must have type 2 diabetes mellitus that has been diagnosed for at least three months.
• Must be taking either (1) no medication for their diabetes or (2) taking metformin, a sulfonylurea, or metformin and a sulfonylurea.
• Subjects must be willing to wash-out of these medications for 14 days prior to the start of the study.
• Subjects must have a BMII between 25 and 40 kg/m² and weigh at leas 50kg.
• Women must be of non-childbearing potential.

Exclusion criteria:

• Laboratory values that meet certain criteria (for example, total cholesterol > 240 mg/dL).
• Clinically significant hepatic enzyme elevation.
• Fasting plasma glucose greater than 240mg/dL.
• Positive test result for Hepatitis B surface antigen, positive Hepatitis C or HIV.
• Any major illness other than diabetes.
• Previous use of insulin as treatment for diabetes.
• Significant renal disease as defined by screening lab tests.
• History of drug or other allergy, which in the opinion of the investigator contradicts subject participation.
• Smoking or use of nicotine-containing products within the previous 6 months.
• History of alcohol or drug abuse.
• Unwilling to abstain from alcohol during the study.
• Unwilling to abstain from caffeine- or xanthine-containing products during the study.
• Use of St. John's Wort during the study.
• Has donated 500 nL or more blood within 56 days of dosing or plans to donate blood in the month following study participation.
• Previously received any GLP-1 mimetic that has moe than 70% sequence homology to GLP-1.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.