A Randomized Trial of a Home System to Reduce Nocturnal Hypoglycemia in Type 1 Diabetes

  1. for the In Home Closed Loop Study Group*
  1. 1Barbara Davis Center for Childhood Diabetes, Aurora, CO
  2. 2Jaeb Center for Health Research, Tampa, FL
  3. 3Stanford University, Stanford, CA
  4. 4St. Joseph’s Health Care, London, Ontario, Canada
  5. 5Rensselaer Polytechnic Institute, Troy, NY
  1. Corresponding author: Roy W. Beck, rbeck{at}


OBJECTIVE Overnight hypoglycemia occurs frequently in individuals with type 1 diabetes and can result in loss of consciousness, seizure, or even death. We conducted an in-home randomized trial to determine whether nocturnal hypoglycemia could be safely reduced by temporarily suspending pump insulin delivery when hypoglycemia was predicted by an algorithm based on continuous glucose monitoring (CGM) glucose levels.

RESEARCH DESIGN AND METHODS Following an initial run-in phase, a 42-night trial was conducted in 45 individuals aged 15–45 years with type 1 diabetes in which each night was assigned randomly to either having the predictive low-glucose suspend system active (intervention night) or inactive (control night). The primary outcome was the proportion of nights in which ≥1 CGM glucose values ≤60 mg/dL occurred.

RESULTS Overnight hypoglycemia with at least one CGM value ≤60 mg/dL occurred on 196 of 942 (21%) intervention nights versus 322 of 970 (33%) control nights (odds ratio 0.52 [95% CI 0.43–0.64]; P < 0.001). Median hypoglycemia area under the curve (AUC) was reduced by 81%, and hypoglycemia lasting >2 h was reduced by 74%. Overnight sensor glucose was >180 mg/dL during 57% of control nights and 59% of intervention nights (P = 0.17), while morning blood glucose was >180 mg/dL following 21% and 27% of nights, respectively (P < 0.001) and >250 mg/dL following 6% and 6%, respectively. Morning ketosis was present <1% of the time in each arm.

CONCLUSIONS Use of a nocturnal low-glucose suspend system can substantially reduce overnight hypoglycemia without an increase in morning ketosis.


  • * A complete list of the members of the In Home Closed Loop Study Group can be found in the Supplementary Data online.

  • Received September 11, 2013.
  • Accepted March 8, 2014.

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This Article

  1. Diabetes Care
  1. Supplementary Data
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