The objective of this cross over study is to access if continuous glucose monitoring (CGMS) with a real time feed back and hypoglycemic as well as hyperglycemic glucose alerts vs. only retrospective analysis of glucose values is able to improve course of glucose with special regard to time spent in hypoglycemic glucose ranges in type 1 diabetic patients with impaired hypoglycemia awareness or a history of severe hypoglycemia. The second objective is to access satisfaction with CGMS during both conditions Condition Type 1 Diabetes Hypoglycemia Intervention Procedure: Real time access to current glucose value Verified by Forschungsinstitut der Diabetes Akademie Mergentheim April 2007 Sponsored by: Forschungsinstitut der Diabetes Akademie Mergentheim Information provided by: Forschungsinstitut der Diabetes Akademie Mergentheim ClinicalTrials.gov Identifier: NCT00467688