Inclusion Criteria:

• Clinical diagnosis of type 1 diabetes and using daily insulin therapy for at least one year The diagnosis of type 1 diabetes is based on the investigator's judgment; C peptide level and antibody determinations are not needed.
• Age 3.0 years to less than 18.0 years
• Subject has used a downloadable insulin pump or Lantus with MDI of a short-acting insulin (e.g. Humalog or Novolog) for at least 6 months
• Parent/guardian and subject understand the study protocol and agree to comply with it
• Subjects >9.0 years old and primary care giver (i.e., parent or guardian) comprehend written English
• Subject has a home computer with email access
• For females, subject not intending to become pregnant during the next 3 months
• No expectation that subject will be moving out of the area of the clinical center during the next 3 months
• Informed Consent Form signed by the parent/guardian and Child Assent Form signed by the subject

Exclusion Criteria:

• The presence of a significant medical disorder that in the judgment of the investigator will affect the wearing of the sensors or the completion of any aspect of the protocol.

• The presence of any of the following diseases:

  • Asthma if treated with systemic or inhaled corticosteroids in the last 6 months
  • Cystic fibrosis
  • Other major illness that in the judgment of the investigator might interfere with the completion of the protocol (Adequately treated thyroid disease and celiac disease do not exclude subjects from enrollment)
• Inpatient psychiatric treatment in the past 6 months for either the subject or the subject's primary care giver (i.e., parent or guardian).
• Current use of oral/inhaled glucocorticoids or other medications, which in the judgment of the investigator would be a contraindication to participation in the study.