This is a randomized, placebo-controlled, double-blind study to evaluate the efficacy, safety, and pharmacodynamics (PD) of multiple doses of REMD-477 in subjects who have Type 1 diabetes and are currently receiving insulin treatment. This study will determine whether REMD-477 can decrease daily insulin requirements and improve glycemic control after 12 weeks of treatment in subjects diagnosed with Type 1 diabetes with fasting C-peptide < 0.2 ng/mL at Screening.