• Change From BL to Week 4 in Fasting Plasma Glucose (FPG) [ Time Frame: BL, 4 weeks (end of double-blind treatment period) ] [ Designated as safety issue: No ]
• Change From BL to Week 4 in 2-hr Glucose Area Under The Curve (AUC) [ Time Frame: BL, 4 weeks (end of double-blind treatment period) ] [ Designated as safety issue: No ]
• Change From BL to Week 4 in the 2-Hour Total GLP-1 Total AUC [ Time Frame: BL, 4 weeks (end of double-blind treatment period) ] [ Designated as safety issue: No ]
  Glucagon-Like Peptide-1 (GLP-1) is an incretin hormone that acts as a potent insulin secretegogue in response to nutrient ingestion and stimulates glucose disposition. The total AUC of Total GLP-1 levels was calculated from blood sample data measured after the morning meal.
• Change From BL to Week 4 in the 2-Hour Active GLP-1 Total AUC [ Time Frame: BL, 4 weeks (end of double-blind treatment period) ] [ Designated as safety issue: No ]
  GLP-1 is cleaved from proglucagon to form the active peptide GLP-1. The active form promotes suppression of glucagon secretion. The total AUC of Active GLP-1 levels was calculated from blood sample data measured after the morning meal.

This study will test the effectiveness and safety of treatment with MK-0893 in combination with other drugs commonly used to treat type 2 diabetes for a duration up to 13 weeks.

• Drug: MK-0893
  Initial loading dose of 200 mg MK-0893 at randomization, followed by MK-0893 administered orally as 40 mg tablets daily throughout the double-blind treatment period (4 weeks).
• Drug: Sitagliptin
  Sitagliptin Phosphate administered orally as 100 mg tablets daily before the morning meal throughout the double-blind treatment period (4 weeks).
  Other Names:

  • Sitagliptin
  • JANUVIA™
  • MK0431
• Drug: Metformin
  Metformin taken orally (500 mg tablets) over an initial 2-week titration period starting at 500 mg administered twice daily before the morning and evening meals, increasing to 1500 mg daily, and ending with 1000 mg twice daily. Metformin then administered throughout the double-blind treatment period (4 weeks).
  Other Names:

  • Metformin
  • GLUCOPHAGE®
• Drug: Placebo for MK-0893
  Matching placebo for MK-0893 was orally administered for the loading dose (200 mg) and for the following daily treatment (40 mg) over the 4 week double blind treatment period.
• Drug: Placebo for Sitagliptin
  Matching placebo for Sitagliptin (100 mg) administered orally as 100 mg tablets daily before the morning meal throughout the double-blind treatment period (4 weeks).
• Drug: Placebo for Metformin
  Metformin-matched placebo taken orally (500 mg tablets) over an initial 2-week titration period starting at 500 mg administered twice daily before the morning and evening meals, increasing to 1500 mg daily, and ending with 1000 mg twice daily. Metformin-matched placebo then administered throughout the double-blind treatment period (4 weeks).

• Experimental: MK-0893 + Sitagliptin
  Interventions:

  • Drug: MK-0893
  • Drug: Sitagliptin
  • Drug: Placebo for Metformin
• Experimental: MK-0893 + Metformin
  Interventions:

  • Drug: MK-0893
  • Drug: Metformin
  • Drug: Placebo for Sitagliptin
• Active Comparator: Sitagliptin + Metformin
  Interventions:

  • Drug: Sitagliptin
  • Drug: Metformin
  • Drug: Placebo for MK-0893

Inclusion Criteria:

• Participants who have Type 2 Diabetes Mellitus, with suboptimal glucose control, while either not on AHA (antihyperglycemic agent) therapy or on monotherapy or on low-dose combination therapy

Exclusion Criteria:

• Participants have a history of Type 1 Diabetes Mellitus
• Participants taking insulin or thiazolidinediones (TZDs: peroxisome proliferator-activated receptor [PPAR]-gamma agonists)
• Participants who have a contraindication to metformin or sitagliptin