Efficacy and Safety of Ertugliflozin (MK-8835/PF-04971729) With Sitagliptin in the Treatment of Participants With Type 2 Diabetes Mellitus (T2DM) With Inadequate Glycemic Control on Diet and Exercise (MK-8835-017)

Inclusion Criteria: * Type 2 diabetes mellitus as per American Diabetes Association guidelines * Not on antihyperglycemic agent (AHA) \>=8 weeks with a Visit 1/Screening HbA1C \>=8.0% and \<=10.5% (\>=64 mmol/mol and \<=91 mmol/mol) OR on single allowable AHA (allowable AHAs prior to screening are: metformin, α-glucosidase inhibitors, sulfonylureas and glinides) with a Visit 1/Screening HbA1C \>=7.5% and \<=10.0% (\>=58 mmol/mol and \<=86 mmol/mol) OR on low-dose dual combination therapy (≤50% of maximum labeled dose of an AHA) with allowable AHAs with a Visit 1/Screening HbA1C \>=7.5% and \<=10.0% (\>=58 mmol/mol and \<=86 mmol/mol) * Body mass index (BMI) \>=18.0 kg/m\^2 * Male or female not of reproductive potential * Female of reproductive potential who agrees to (or have their partner agree to) remain abstinent from heterosexual activity or to use 2 acceptable combinations of contraception. Exclusion Criteria: * History of type 1 diabetes mellitus or diabetic ketoacidosis * History of other specific types of diabetes (e.g., genetic syndromes, secondary pancreatic diabetes, diabetes due to endocrinopathies, drug- or chemical-induced, and post-organ transplant * A known hypersensitivity or intolerance to any sodium glucose co-transporter (SGLT2) inhibitor or sitagliptin * Has been treated with any of the following agents within 12 weeks of study start or during the pre-randomization period: insulin of any type (except for short-term use \[i.e., \<=7 days\] during concomitant illness or other stress), other injectable anti-hyperglycemic agents (e.g., pramlintide, exenatide, liraglutide), pioglitazone or rosiglitazone, other sodium glucose co-transporter 2 (SGLT2) inhibitors, dipeptidyl-peptidase 4 inhibitors (DPP-4 inhibitors), bromocriptine (Cycloset™), colesevelam (Welchol™), any other AHA with the exception of the protocol-approved agents * Is on a weight-loss program or weight-loss medication or other medication associated with weight changes and is not weight stable prior to study start * Has undergone bariatric surgery within the past 12 months or \>12 months and is not weight stable prior to study start * A history of myocardial infarction, unstable angina, arterial revascularization, stroke, transient ischemic attack, or New York Heart Association (NYHA) functional Class III-IV heart failure within 3 months of study start * Active, obstructive uropathy or indwelling urinary catheter * History of malignancy \<=5 years prior to study start, except for adequately treated basal cell or squamous cell skin cancer or in situ cervical cancer * A known history of human immunodeficiency virus (HIV) * A blood dyscrasia or any disorder causing hemolysis or unstable red blood cells, or a clinically important hematological disorder (e.g. aplastic anemia, myeloproliferative or myelodysplastic syndromes, thrombocytopenia) * A medical history of active liver disease (other than non-alcoholic hepatic steatosis), including chronic active hepatitis B or C, primary biliary cirrhosis, or symptomatic gallbladder disease * Any clinically significant malabsorption condition * Current treatment for hyperthyroidism * On thyroid replacement therapy and not on a stable dose for at least 6 weeks prior study start * On a previous clinical study with ertugliflozin * Participated in other studies involving investigational drug(s) 30 days prior to study start * Surgical procedure within 6 weeks prior to study start or major surgery planned during the trial * Positive urine pregnancy test * Pregnant or breast-feeding, or planning to conceive during the trial, including 14 days following the last dose of study medication * Planning to undergo hormonal therapy in preparation for egg donation during the trial, including 14 days following the last dose of study medication * Routinely consumes \>2 alcoholic drinks per day or \>14 alcoholic drinks per week or engages in binge drinking * Donated blood or blood products within 6 weeks of study start.