Read the current Defeat Diabetes® E-Lerts™ Newsletter

This website is certified by Health On the Net Foundation. Click to verify.
This site complies with the HONcode standard for trustworthy health information:
verify here.

 
 
 
     
    
      
       
Defeat Diabetes
Foundation
150 153rd Ave,
Suite 300

Madeira Beach, FL 33708
  

Artificial Pancreas Improves Glucose Control

Posted: Sunday, February 14, 2010

Closed-loop insulin delivery systems can improve overnight blood sugar control and reduce hypoglycemia risk in young patients with Type 1 diabetes, researchers have found.

More patients with this "artificial pancreas" maintained target blood glucose levels over the course of the night than those on standard insulin pumps (60% versus 40%), according to Roman Hovorka, MD, of Addenbrooke's Hospital in Cambridge, England, and colleagues.

They also avoided significant hypoglycemia events, while those on standard therapy had nine, the researchers reported. "Overnight closed-loop delivery is appealing because it addresses the issue of nocturnal hypoglycemia," they wrote.

Two management strategies for Type 1 diabetes -- continuous glucose monitoring devices and insulin pumps -- can be combined to form closed-loop systems. This enables delivery of insulin determined by an algorithm using real-time sensor glucose data, rather than preprogrammed rates.

Unfortunately, few prototypes have been developed, the researchers wrote, because progress has been hindered by suboptimum accuracy and reliability of monitoring devices, slow absorption, and inadequate control algorithms. So, to test whether these devices were effective overnight, the researchers conducted three randomized crossover studies at the Wellcome Trust Clinical Research Facility at Addenbrooke's Hospital in Cambridge.

They assessed 17 patients, ages 5 to 18, with Type 1 diabetes. During 54 nights in the hospital (33 nights on closed-loop devices, and 21 on standard insulin pumps), they monitored three different crossover groups: standard versus closed-loop delivery, closed-loop delivery after rapidly or slowly absorbed meals, and standard versus closed-loop delivery after exercise.

In the closed-loop scenario, glucose measurements were fed to a control algorithm every 15 minutes, and a nurse adjusted the insulin pump. In the first group, the researchers found no significant differences for time in the targeted glucose range or hypoglycemic events (<3.90 mmol/l) between closed-loop and standard delivery (52% versus 39% and 1% versus 2%, respectively). Nor were there differences in maintaining the targeted range for closed-loop patients after they ate their meals rapidly or slowly (53% versus 55%).

"In our studies, postprandial glucose concentrations were increased after large evening meals, but overall glucose control was unaffected and risk of hypoglycemia was low, documenting effective, nonaggressive insulin delivery," the researchers wrote.

Patients in the closed-loop delivery group who did early-evening exercises spent the greatest percentage of time in the target blood glucose range, but the improvement was not significant at the corrected level, the researchers said (78% versus 43%).

"Moderate-intensity, late-afternoon or early-evening exercise in young people is a frequent occurrence and increases glucose requirements in the early morning, exacerbating the risk of nocturnal hypoglycemia," they wrote. "Our closed-loop algorithm ameliorated this risk and maintained good glucose control."

A secondary analysis of pooled data showed increased time in the target range and reduced hypoglycemia episodes for patients with the "artificial pancreas," compared with those on the regular insulin pump (60% versus 40%, P=0.002, and 2.1% versus 4.1%, P=0.03, respectively).

The closed-loop device also completely prevented blood glucose levels from falling below 3.0 mmol/l, which represents "significant hypoglycemia," the researchers wrote. There were nine such events in the control group.

They acknowledged that adoption of closed-loop devices is "likely to be gradual," but "advancements in glucose-sensing technologies could further improve the performance of closed-loop systems."

In the future, fully automated closed-loop insulin delivery will "need wireless data transmission to replace manual control of the pump by nurses."

In an accompanying editorial, Eric Renard, MD, of the Center Hospitalier Universitaire de Montpellier in France, called the findings a "milestone in the quest for an artificial pancreatic beta-cell that started almost 50 years ago." But he cautioned that glucose control at mealtimes "will now be the challenge for Hovorka and co-workers and other research groups who adopted model predictive control algorithms."

"Because of the more complex effects that need to be considered for meal coverage, including the cephalic phase of insulin secretion, incretin's effects, and the variability of gut glucose absorption from mixed meals, model predictive control algorithms could offer more flexibility than do proportional-integral-derivative algorithms."

Meanwhile, Renard wrote, "Overnight closed-loop insulin delivery will hopefully be implemented at home."

Practice Pearl: 

Explain that more patients on a closed-loop insulin delivery system maintained target blood glucose levels over the course of the night than those on standard insulin pump delivery. They also had a reduced risk of hypoglycemia.

Source: Diabetes In Control: Hovorka R, et al "Manual closed-loop insulin delivery in children and adolescents with Type 1 diabetes: a phase 2 randomized crossover trial" Lancet 2010; DOI: 10.1016/S0140-6736(09)61998-X.

 
 
 
 
 
Join us on Facebook
 
 
 

Send your unopened, unexpired diabetes testing supplies to:

Defeat Diabetes Foundation
150 153rd Ave, Suite 300
Madeira Beach, FL 33708

 

DDF advertisement
 

 Friendly Banner
 


Friendly Banner
 
 
 
Analyze nutrition content by portion
DDF advertisement