A Study of the Efficacy and Safety of MK-0431D (a Fixed-dose Combination of Sitagliptin and Simvastatin) for the Treatment of Participants With Type 2 Diabetes Mellitus (T2DM) With Inadequate Glycemic Control on Metformin Monotherapy (MK-0431D-266)

Inclusion Criteria: * has T2DM * (1) Male; (2) female not of reproductive potential; or (3) female of reproductive potential who agrees to remain abstinent or use alone or in conjunction with their partner 2 methods of contraception to prevent pregnancy during the study and for 14 days after the last dose of study drug * is currently on metformin monotherapy at a daily dose of at least 1500 mg for at least 10 weeks * is not on a lipid-lowering agent for at least 6 weeks prior to entering the study Exclusion Criteria: * has history of type 1 diabetes mellitus (T1DM), or a history of ketoacidosis or possibly has T1DM * has been on a thiazolidinedione (TZD) within the previous 16 weeks * has been treated with a statin or other lipid-lowering agent (including over-the-counter \[OTC\] supplements) within the previous 6 weeks * currently participating in or has participated in another clinical study within the past 12 weeks * intends to consume \>1.2 liters of grapefruit juice daily during the study * is on or likely to require treatment for at least 2 consecutive weeks or repeated courses of corticosteroids (inhaled, nasal and topical corticosteroids are permitted) * intolerance or hypersensitivity to sitagliptin, simvastatin, metformin or glimepiride * is on a weight loss program and not in the maintenance phase or has started a weight loss medication or has undergone bariatric surgery in the previous 12 months * has undergone a surgical procedure in the past 4 weeks or planned major surgery during the study * has symptomatic hyperglycemia that requires immediate initiation, adjustment, or addition of antihyperglycemic therapy * has a history of myopathy or rhabdomyolysis with any statin * has cardiovascular disease, a diagnosis of congestive heart failure, or uncontrolled high blood pressure * has a history of active liver disease * has chronic progressive neuromuscular disorder, human immunodeficiency virus (HIV), hematological disorder, or uncontrolled endocrine or metabolic disease * is currently being treated for hyperthyroidism or is on thyroid hormone therapy and has not been on a stable dose for at least 6 weeks * has a history of malignancy in the previous 5 years (excluding adequately treated basal cell or squamous cell skin cancer or in situ cervical cancer) * is pregnant or breast feeding, or is expecting to conceive or donate eggs during the course of the study, including 14 days after the last dose of study drug * is a user of recreational or illicit drugs or has had a recent history of drug abuse * consumes \>2 alcoholic drinks per day or \>14 alcoholic drinks per week, or engages in binge drinking