A Study to Test the Safety and Efficacy of Adding Sitagliptin in Patients With Type 2 Diabetes Mellitus (MK0431-074)

A Phase III, Multicenter, Double-Blind, Placebo-Controlled, Randomized Study to Evaluate the Safety and Efficacy of the Addition of Sitagliptin 100 mg Once Daily in Patients With Type 2 Diabetes With Inadequate Glycemic Control on Metformin Monotherapy

A study to assess the safety and efficacy of the addition of sitagliptin compared to placebo in patients with Type 2 Diabetes Mellitus who have inadequate glycemic control on metformin.

Inclusion Criteria:

• 18 - 78 years of age
• Currently on metformin monotherapy

Exclusion Criteria:

• History of Type 1 diabetes mellitus or ketoacidosis
• Currently on a weight loss program and not in the maintenance phase or has started on a weight loss medication within the last 8 weeks
• Has undergone surgery requiring general anesthesia within the past 4 weeks or has planned major surgery
• Currently participating in a study or has participated in a study with or without an investigational compound or device within the past 12 weeks
• History of active liver disease such as chronic active hepatitis B or C, cirrhosis or symptomatic gallbladder disease
• HIV positive
• Pregnant, breast-feeding or planning to become pregnant during the study
• User of recreational or illicit drugs or has a recent history (within the past year) of drug or alcohol abuse or dependence