This study will help determine the frequency and magnitude of nocturnal hypoglycemia (low blood sugar at night during sleep), in children with type 1 diabetes who are on a standard insulin regimen, by using a Continuous Glucose Monitoring System (CGMS). Secondary objectives include the establishment of a definition of nocturnal hypoglycemia for the CGMS and for the calculation of sample size needed for future studies using CGMS. Nocturnal hypoglycemia (NH) can be associated with significant morbidity including seizure and coma. The investigators intend to use the CGMS in a future study investigating the use of a new insulin combination aimed to decrease the frequency of NH in the pediatric population.

Thirty pediatric subjects with established type 1 diabetes mellitus will be asked to wear a CGMS for 3 days. During this time the participants will be required to test and record self-monitored blood glucose readings at designated time periods and if they have symptoms of hypoglycemia. The comparison of these values with each other and with different previously defined values of NH will allow for a clear definition of NH to be made. A survey has also been designed to assess participant satisfaction with the CGMS.

Inclusion Criteria:

• Type 1 diabetes
• less than 18 years of age
• >2 year duration of diabetes
• on a conventional TID insulin regimen (morning and bedtime NPH) for a minimum of 3 months
• informed consent and assent

Exclusion Criteria:

• medical conditions other than treated hypothyroidism or asthma requiring oral glucocorticoids more than once per year
• intention to move outside of CHEO's catchment area within the next 4 months
• more than 17 years of age and unwilling to continue receiving diabetes care at CHEO until study completion
• intention to switch to a different insulin regimen prior to study completion

Children and adolescents with type 1 diabetes