The Safety and Efficacy of MK-1293 Versus Lantus™ in Participants With Type 2 Diabetes Mellitus (MK-1293-006)

Inclusion Criteria: * Diagnosis of Type 2 Diabetes Mellitus (T2DM) as defined by the American Diabetes Association (ADA) or the European Association for the Study of Diabetes (EASD) * hemoglobin A1C of ≤11.0% and requires insulin for glycemic control * Body mass index (BMI) \<45 kg/m\^2 Exclusion Criteria: * History of type 1 diabetes mellitus or a history of ketoacidosis, or has type 1 diabetes confirmed with a C-peptide \<0.7 ng/mL (0.23 nmol/L) * One or more severe hypoglycemic episodes associated with hypoglycemic seizures, comas or unconsciousness within the past 6 months * History of intolerance or hypersensitivity to Lantus™ or contraindication to Lantus™ or one of its excipients based on the label of the country of the investigational site * On a weight loss program within the last 8 weeks * Received injectable incretin-based therapy (e.g., Victoza™, Byetta™) within the prior 8 weeks * Bariatric surgery within 12 months prior to signing the informed consent * Likely to require treatment for ≥2 consecutive weeks or repeated courses of corticosteroids * Undergone a surgical procedure within 4 weeks prior to signing informed consent or has planned major surgery during the study * New or worsening signs or symptoms of coronary heart disease or congestive heart failure within the last 3 months * Presence of any of the following during the last 3 months: acute coronary syndrome, coronary artery intervention, and/or stroke or transient ischemic neurological disorder * Severe peripheral vascular disease * Systolic blood pressure ≥ 160 mm Hg or a diastolic ≥95 mm Hg and blood pressure is not considered likely to be under these limits with an adjustment in antihypertensive medication * Chronic myopathy or a progressive neurological or neuromuscular disorder * Active nephropathy * 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 * Human immunodeficiency virus (HIV) * Clinically important hematological disorder (such as aplastic anemia, myeloproliferative or myelodysplastic syndromes, thrombocytopenia) * History of malignancy ≤5 years prior to signing informed consent, except for adequately treated basal cell or squamous cell skin cancer, or in situ cervical cancer * History of melanoma, leukemia, lymphoma, or renal cell carcinoma * Hyperthyroidism * On a stable dose of thyroid hormone replacement therapy for \<6 weeks * Uses recreational or illicit drugs or has had a recent history (within the last year) of drug or alcohol abuse or dependence * Pregnant or breast-feeding, or is expecting to conceive or donate eggs during the study, including 14 days following the last dose of study drug * Donated blood products or has had phlebotomy of \>300 mL within 8 weeks of signing informed consent, or intends to donate blood products within the projected duration of the study * Poor mental function or any other reason to expect that the participant may have difficulty in complying with the requirements of the study * Clinically significant ECG abnormality which exposes the participant to risk by enrolling in the study * Positive urine pregnancy test * Participant is a night shift worker which causes difficulty complying with the overnight fast requirement and has potential for confounding the 7-point SMBG analysis * Participant, as assessed by the investigator, is not appropriate for or does not agree to target a fasting glucose of 70-100 mg/dL \[3.9 -5.6 mmol/L\] * Has used a formulation of glargine insulin other than Lantus™