This study will evaluate the efficacy, safety, tolerability, and pharmacokinetics of GK Activator (2) in combination with metformin, compared to that of placebo (metformin monotherapy), in patients with type 2 diabetes mellitus. Patients will continue on their stable dose of metformin and will be randomized to receive either GK Activator (2) or placebo. The anticipated time on study treatment is less than 3 months, and the target sample size is 100-500 individuals.

Inclusion Criteria:

• adult patients 30-75 years of age;
• type 2 diabetes mellitus;
• individual maximal tolerated daily dose of metformin monotherapy for >=3 months prior to screening.

Exclusion Criteria:

• type 1 diabetes mellitus;
• any oral anti-hyperglycemic medication, other than metformin monotherapy, during last 3 months