The purpose of this study is to evaluate whether the within-subject variation in duration of action and time-action profile of glargine measured by isoglycemic clamp will be below prespecified levels.

Inclusion Criteria:

Part 1:

• Patient is a male between 18 to 45 years of age (inclusive) at the prestudy (screening) visit
• Patient has a clinical diagnosis of type 1 diabetes
• Patient must have been treated with insulin since diagnosis and be on a stable dose of insulin
• Patient has a Body Mass Index (BMI) of <=27 kg/m2 and >18 kg/m2
• Patient has been a nonsmoker and/or has not used nicotine or nicotine-containing products for at least approximately 6 months

Part 2:

• Subject is a male between 18 to 45 years of age at the prestudy (screening) visit
• Subject has a Body Mass Index (BMI) of <=25 kg/m^2
• Subject has been a nonsmoker and/or has not used nicotine or nicotine-containing products for at least approximately 6 months

Exclusion Criteria:

Part 1:

• Patient has a history of stroke, chronic seizures, or major neurological disorder
• Patient has currently active and untreated clinically significant endocrine, cardiovascular, hematological, hepatic, renal, respiratory, or genitourinary abnormalities or diseases
• Patient has a history of hypertension requiring treatment
• Patient has a history of neoplastic disease within the past 5 years
• Patient is currently being treated with, or has a history of treatment with any oral antihyperglycemic agent
• Patient has a history of significant multiple and/or severe allergies

Part 2:

• Subject has a history of stroke, chronic seizures, or major neurological disorder
• Subject has a history of hypertension requiring treatment
• Subject has a history of neoplastic disease within the past 5 years
• Subject has history of diabetes (Type 1, Type 2 or steroid-induced) or family history of diabetes mellitus
• Subject has a history of hypersensitivity to glargine or any of its inactive ingredients