The purpose of this study is to determine what the effects are of real-time continuous glucose monitoring on glycemia and quality of life in patients with type 1 diabetes mellitus and impaired hypoglycemia awareness.

The investigators hypothesize that the use of RT-CGM, relative to a control intervention using masked CGM, will result in improvement of various measures of glycemia and indicators of quality of life, reduce the occurrence of hypoglycemia and hyperglycemia and restore hypoglycemia awareness in T1DM patients with IHA. We will test this hypothesis by addressing the following research questions:

What is the effect of 16 weeks of RT-CGM use, versus 16 weeks of CGM use, in patients with T1DM and IHA on

1. (primary objective:) time spent in euglycemia

2. (secondary objectives:)

   • (diabetes-specific) markers of QoL, covering diabetes-related emotional distress (PAID-5), fear of hypoglycemia (HFS-2), self-efficacy (CIDS), health status (EQ5D) and emotional well-being (WHO-5)
   • other glycemia variables, including HbA1c and time spent in hypo- and - hyperglycemia ranges
   • the incidence and duration of hypoglycemic episodes
   • changes in hypoglycemia awareness score according to Gold et al.,

3. (tertiary objectives:)

   • measures of glucose variability
   • the autonomic nervous system balance
   • the duration of wear of the RT-CGM device
   • patients' therapy adjustments during the interventions
   • hypoglycemia awareness scores according to Clarke et al.
   • satisfaction with use of CGM
   • the number of contact moments not planned according to the study schedule
   • absence of work of patient (and spouse)
   • the global estimated costs of use of health care

Inclusion Criteria:

• T1DM, diagnosed according to ADA criteria regardless duration
• Use of multiple daily injections of insulin (with a basal insulin injection and bolus injections) or continuous subcutaneous insulin infusion
• Any HbA1c
• Age between 18 and 70 years old (inclusive)
• IHA according to the questionnaire by Gold et al.
• Performing at least 3 SMBG/day or 21 SMBG/week

Exclusion Criteria:

• Type 2 diabetes mellitus
• History of (recent) major renal, liver, or (ischemic) heart disease (including cardiac conduction disorders)
• Current untreated proliferative diabetic retinopathy
• Current (treatment for) malignancy
• Current use of non-selective beta-blockers
• Current psychiatric disorders, including schizophrenia, bipolar disorder, anorexia nervosa or bulimia nervosa
• Substance abuse or alcohol abuse (men >21 units/week, women >14 units/week)
• Current pregnancy or intention to conceive
• Current use of RT-CGM other than for short term (i.e. diagnostic use or use shorter than 3 consecutive months)
• Hearing or vision impairment hindering perceiving of glucose display and alarms, or otherwise incapable of using a (RT-)CGM, in the opinion of the investigator
• Poor commandment of the Dutch language or any (mental) disorder that precludes full understanding of the purpose and instructions of the study
• Participation in another clinical study
• Known or suspected allergy to trial product or related products