The primary objective of the study is to determine if CGM can reduce hypoglycemia and improve quality of life in older adults with T1D.

Reducing hypoglycemia is an important aspect of management of T1D in older adults, many of whom have hypoglycemic unawareness, cognitive impairment, or both. CGM offers the opportunity to reduce hypoglycemia and its related complications such as fractures from falls and hospitalizations and improve quality of life including reducing hypoglycemic fear and diabetes distress. Despite these potential benefits, CGM is used by only a small proportion of older adults with T1D. Previous studies assessing CGM efficacy have included only a small number of adults ≥ 60 years of age, excluded patients most prone to severe hypoglycemia, focused on improving HbA1c rather than hypoglycemia, and used older generation CGM sensors. These studies are not generalizable to the population of older adults with T1D. The potential benefit of CGM in reducing hypoglycemia in the older adult population has not been well studied. The goal of this study is to assess the potential benefits and risks of CGM in older adults with T1D.

Inclusion Criteria:

To be eligible for the study, all participants must meet the following criteria:

1. Clinical diagnosis of insulin dependent presumed autoimmune type 1 diabetes by the investigator and meeting at least one of the following criteria:

   i. Age > 6 months and < 10 years old at diagnosis OR ii. Positive pancreatic autoantibodies at any time (GAD-65, IA-2, ICA or ZnT8) or positive anti-insulin autoantibody at diagnosis only (within 10 days of starting insulin) OR iii. Presence of 2 or more of the following clinical indicators suggestive of type 1 diabetes:

   1. Age at diagnosis < 40 years
   2. Non-obese at diagnosis according to BMI (< 95th percentile pediatric and < 30 kg/m2 adult)
   3. Diabetic ketoacidosis (DKA) at any time,
   4. Plasma C-peptide level < 0.8 ng/ml (with blood glucose > 80 mg/dL if available) at any time
   5. Family history of type 1 diabetes in a first degree relative (parent, sibling, or child).

2. Age ≥60 years

3. HbA1c <10.0% at screening or within 30 days prior to screening visit (the upper limit was selected as a surrogate measure of likelihood of adherence to the protocol with the belief that those with higher HbA1c levels are generally noncompliant with diabetes management and thus not good candidates for the trial)

4. Insulin regimen involves either use of an insulin pump (a minimum of 40% of study population) or multiple daily injections of insulin (minimum of 40% of study population).

5. Participant is able to manage his/her diabetes with respect to insulin administration and glucose monitoring (which may include assistance from spouse or other caregiver)

6. Participant understands the study protocol and agrees to comply with it

7. Participant comprehends written and spoken English

8. At least 240 hours (10 out of 14 days) of sensor glucose data with appropriate number of calibrations from the blinded CGM pre-randomization phase

Exclusion Criteria:

Individuals meeting any of the following exclusion criteria at baseline will be excluded from study participation.

1. Use of unblinded CGM, outside of a research study, as part of real-time diabetes management in the last 3 months
2. At least 10% of time spent with sensor glucose levels < 54 mg/dl during the blinded CGM screening period AND a severe hypoglycemic event in the past 6 months (a severe hypoglycemic event that required assistance of another person due to altered consciousness, and required another person to actively administer carbohydrate, glucagon, or other resuscitative actions (see section 8.1).
3. Extreme visual or hearing impairment that would impair ability to use real-time CGM assessed at screening visit
4. Known adhesive allergy or skin reaction during the blinded CGM pre-randomization phase that would preclude participation in the randomized trial
5. Plans to begin non-insulin medication for blood glucose lowering during the course of the study
6. Stage 4 or 5 renal disease or most recent GFR < 30 ml/min/m2 from local lab within the past 6 months
7. The presence of a significant medical or psychiatric condition or use of a medication that in the judgment of the investigator may affect completion of any aspect of the protocol, or is likely to be associated with life expectancy of <1 year.
8. Clinical diagnosis of dementia (cognitive impairment that is mild and not considered sufficient for diagnosis of dementia is acceptable)
9. Need for use of acetaminophen or acetaminophen-containing products on a regular basis during the 6 months of the trial (unless stipulation no longer required with use of newer generation sensors)
10. Inpatient psychiatric treatment in the past 6 months
11. Participation in an intervention study (including psychological studies) in past 6 weeks.
12. Expectation that participant will be moving out of the area of the clinical center during the next 6 months, unless the move will be to an area served by another study center.