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Predictive hyperglycemia minimization safe, effective for overnight glucose control
In people with type 1 diabetes, the addition of a predictive hyperglycemia minimization component to a predictive low-glucose insulin suspension alone system was safe and effective in maintaining overnight glucose control, study data show.
“We developed this system with the concept that there should be minimal alarms, and they should only be for severe hypo- and hyperglycemia,” Tamara Spaic, MD, MSc, FRCPC, medical director of the Diabetes Education Center, assistant professor of endocrinology and metabolism, department of medicine, Western University in Canada, told Endocrine Today. “The system is easy to use and allows patients to have undisturbed sleep and good overnight glucose control. It also allows the patient to override the system at any time they want to if they find a sensor is not working well, or they have eaten a large meal at bedtime and require an increased basal rate of a square wave bolus at bedtime. The system decreases the burden of diabetes management overnight, allowing both a good night’s sleep and waking up with a glucose value in range.”
Spaic, along with John W. Lum, MS, of the Jaeb Center for Health Research in Tampa, Florida, and colleagues evaluated 30 people aged 15 to 45 years with type 1 diabetes randomly assigned to a predictive hyperglycemia and hypoglycemia minimization system or a predictive low-glucose insulin suspension alone each night for 42 nights. Researchers sought to determine the time spent in a sensor glucose range of 70 mg/dL to 180 mg/dL during the overnight period.
Mean time spent in the glucose range of 70 mg/dL to 180 mg/dL was higher during the predictive hyperglycemia and hypoglycemia minimization system (78%) compared with the predictive low-glucose insulin suspension alone (71%; P < .001). Mean overnight glucose concentration was lower during the predictive hyperglycemia and hypoglycemia minimization system (143 mg/dL) compared with the predictive low-glucose insulin suspension alone (152 mg/dL; P < .001).
Both groups had similar median time spent at a concentration less than 70 mg/dL.
Mean morning blood glucose was lower after the predictive hyperglycemia and hypoglycemia minimization system (142 mg/dL) compared with the predictive low-glucose insulin suspension alone (163 mg/dL; P < .001).
No cases of severe hypoglycemia, diabetic ketoacidosis or other serious, study-related or device-related adverse events were reports by any participant during the trial.
“This study of our overnight closed-loop system was conducted while adolescents and adults with type 1 diabetes were sleeping at home and showed that overnight glucose control was significantly improved while decreasing the risk and incidence of nocturnal hypoglycemia,” Spaic told Endocrine Today. “Blood glucose control overnight is always difficult even for the most meticulous patients because they are sleeping and can only make adjustments to their insulin delivery overnight by waking up and modifying insulin disease. The closed-loop system does this automatically, giving small correction doses if their glucose is projected to be high, and stopping insulin delivery if they are at risk for hypoglycemia. Hence, individuals with type 1 diabetes can have both a good night’s sleep and good overnight glucose control.” – by Amber Cox
For more information:
John W. Lum, MS, can be reached at Jaeb Center for Health Research Inc., 15310 Amberly Drive, #350, Tampa, FL 33647; email: jlum@jaeb.org.
Disclosure: Lum reports financial ties with Animas Corp., BigFoot Biomedical, JDRK, NIDDK and Tandem Diabetes Care. Spaic reports various financial ties with AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Janssen-Ortho, JDRF/Federal Development, Johnson & Johnson, Lexicon, Novo Nordisk and Sanofi. Please see the full study for a list of all other authors’ relevant financial disclosures.
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In this interesting study, researchers conducted a 42-night trial in 30 individuals with relatively well-controlled (average HbA1c 7.5%) type 1 diabetes in the age range of 15 to 45 years. Participants were randomly assigned each night to two different versions of closed-loop insulin delivery: either a predictive hyperglycemia and hypoglycemia minimization (PHHM) system or a predictive low-glucose insulin suspension (PLGS) alone system. The system suspended the insulin pump on both the PHHM and PLGS nights for predicted low glucose. In addition, on PHHM nights, the system also delivered correction boluses for predicted high glucose. Compared with PLGS alone, as expected, the PHHM system increased the time spent in the target range (70–180 mg/dL) from 71% to 78% (P < 0.001). The average morning blood glucose concentration was also lower with PHHM (163 mg/dL after PLGS nights vs. 142 mg/dL after PHHM nights). There was no difference in low glucose levels between the two arms. Glucose variability was lower with the PHHM system.
This study compared two different versions of closed-loop systems — one that simply stops insulin delivery during impending hypoglycemia and one that also gives more insulin when glucose was predicted to go high. The system was implemented using a bedside computer with wireless communication to an insulin pump and designed as a simple, safe and low-maintenance add-on system. There were no serious adverse events during the study. During the daytime, participants used the insulin pump with the glucose sensor without the intervention of the system. The study was conducted at home in free-living conditions with no restrictions on exercise, food intake or insulin delivery before or during system use.
Results from this study add to a growing body of evidence showing that closed-loop insulin delivery can achieve better outcomes. Other groups have performed both daytime and nighttime closed-loop studies under free-living conditions showing better results with closed-loop compared with pump therapy combined with glucose sensors. Nocturnal hypoglycemia is particularly worrying, and systems like the one used in this study may help to reduce the risk for dangerously low glucose levels while improving time spent in normal glucose range and reducing time spent with high glucose levels. Such improvements, if sustained in the long term, will lead to fewer diabetes complications, such as kidney failure, blindness and amputations, while improving the quality of life of our patients.