To compare the efficacy (in terms of metabolic control evaluated through HbA1c levels) of treatment with insulin glargine as basal insulin and insulin analogue (insulin lispro) as mealtime insulin with a regimen of insulin NPH as basal insulin with regular insulin, as mealtime insulin, after a 16 week treatment phase with each regimen and to compare the safety of both treatments, evaluated through hypoglycemic rates.

Multicenter, open-label, randomized (allocation ratio 1:1), cross-over with two treatment phases of 16 weeks each in two treatment groups:

• Study arm with insulin glargine + insulin lispro (phase 1) and insulin NPH + regular insulin (phase 2)
• Insulin NPH + regular insulin (phase 1) and insulin glargine + insulin lispro (phase 2)

Inclusion Criteria:

• Subjects with type 1 diabetes mellitus
• 18-65 years of age
• C-Peptide negative
• Treated at least for 6 months with multiple daily doses of insulin and with HbA1c greater than or equal to 7.0% and less than or equal to 9.5% and a BMI less than or equal to 35 kg/m².
• Women of childbearing potential must have a negative pregnancy test in visit 1 and must use an effective contraceptive method during the study.