Prolonged Nocturnal Hypoglycemia Is Common During 12 Months Of Continuous Glucose Monitoring In Children And Adults With Type 1 Diabetes

  1. Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Study Group


Objective: To characterize the amount of nocturnal hypoglycemia and evaluate factors associated with nocturnal hypoglycemia assessed with continuous glucose monitoring (CGM) in adults and children with type 1 diabetes who participated in the JDRF CGM Randomized Clinical Trial.

Research Design and Methods: The analysis included 36,467 nights with ≥4 hours of CGM glucose readings between 12 midnight and 6 a.m. from 176 subjects assigned to the trial's CGM group. The percentage of nights in which hypoglycemia occurred (2 consecutive CGM readings ≤60mg/dL in 20 minutes) was computed for each subject. Associations with baseline characteristics and clinical factors were evaluated using a multivariate regression model.

Results: Hypoglycemic events occurred during 8.5% of nights, with the median percentage of nights with hypoglycemia per subject being 7.4% (interquartile range 3.7% to 12.1%). The duration of hypoglycemia was ≥2 hours on 23% of hypoglycemic nights. In a multivariate model, a higher incidence of nocturnal hypoglycemia was associated with (1) lower baseline HbA1c levels (P<0.001) and (2) the occurrence of hypoglycemia on one or more nights during baseline blinded CGM (P<0.001). The hypoglycemia frequency was not associated with age or with insulin modality (pump versus multiple daily injections).

Conclusions: Nocturnal hypoglycemia is frequent and often prolonged in adults and children with type 1 diabetes. Patients with low HbA1c levels are at an increased risk for its occurrence. One week of blinded CGM can identify patients who are at greater risk for nocturnal hypoglycemia.


    • Received November 11, 2009.
    • Accepted February 8, 2010.

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  1. Diabetes Care
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