Mylan Insulin Glargine Study

This is a multicenter, double-blind, randomized, parallel-group Phase 3 study in subjects with type 1 diabetes mellitus (T1DM) comparing the efficacy, immunogenicity, and safety of MYL-1501D products from 2 manufacturing processes (Process V and Process VI). After a 2-week screening period, all subjects will be titrated on Lantus® during a 4-week run-in period and shifted from their current mealtime insulin to insulin lispro (Humalog®). Subjects will then be randomized (stratified by time of administration of glargine \[morning and evening\]) to 1 of 2 groups: * MYL-1501D product from Process V * MYL-1501D product from Process VI Treatment with MYL-1501D is for 18 weeks. A follow-up visit is scheduled 2 weeks after last dose of MYL 1501D.