Nocturnal Hypoglycemia Frequent & Prolonged with Intensive Treatment

The Juvenile Diabetes Research Foundation Continuous glucose Monitoring (CGM) Study Group assessed the occurrence of nocturnal hypoglycemia and associated risk factors with CGM in 176 children and adults with Type 1 diabetes. All patients were aged 8 years and older, had Type 1 diabetes for at least one year, HbA1c level <10%, and used an insulin pump or had multiple daily insulin injections.  

The analysis included 36,467 nights with four or more hours of CGM glucose readings from midnight to 6 a.m. Researchers collected and assessed the number of nights in which two consecutive CGM readings <60 mg/dL occurred within 20 minutes for each participant.

Nocturnal hypoglycemic events occurred during 8.5% of the nights, with 47% lasting at least one hour, 23% lasting two or more hours and 11% lasting at least three hours. The median percentage of nights with hypoglycemia per patient was 7.4% (interquartile range, 3.7-12.1), about two times per month.

The median rate of hypoglycemia was 6.3% for patients aged 8 to 14 years, 8.8% for patients aged 15 to 24 years and 7.4% for patients aged 25 years and older.

The mean duration of events was shorter in patients aged 25 years and older compared with younger patients (73 minutes vs. 88 minutes; P=.007).

Low HbA1c levels and hypoglycemia during one or more nights with baseline blinded CGM were also associated with a higher incidence of nocturnal hypoglycemia (P<.001 for both), according to multivariate regression model results. Nocturnal hypoglycemia was not associated with age or type of insulin delivery.

"One week of blinded CGM can identify patients who are at greater risk for nocturnal hypoglycemia," the researchers concluded.

Diabetes Care. 2010; 33:1004-1008;Beck RW.