Artificial pancreas effective in regulating glucose in patients with well-controlled type 1 diabetes

This study compared a new method of insulin delivery, a hybrid closed-loop system, with standard insulin pumps in patients with type 1 diabetes (T1D). It was found that the time spent at the desired glucose concentration was improved with the closed-loop system.

A traditional insulin pump is a small device that continuously delivers insulin, without the need for multiple daily injections. An additional bolus injection can be given manually before meals. Continuous glucose monitoring (CGM) systems measure glucose levels throughout the day by placing a sensor in the fat just under the skin.

A closed-loop insulin delivery system is sometimes called an artificial pancreas. This is because they use information from a CGM system to automatically control the release of insulin from a pump. This is similar to how the pancreas changes the amount of insulin it releases when blood-glucose levels change. With hybrid closed-loop systems users also administer a bolus injection before meals. 

Previous studies have found that closed-loop systems improve glucose regulation in patients with T1D. Good regulation of glucose levels is important to reduce the risk of complications of T1D. Research focusing on patients with well-controlled diabetes is limited.

This study included 29 adults with well-controlled T1D, meaning that HbA1c levels (average measure of blood glucose over the last 3 months) were less than 7.5%. All patients had been using traditional insulin pump delivery for at least 6 months before the study. Half of patients were randomly assigned to receive closed-loop insulin delivery for 4 weeks, while the other half continued with their usual method. After a washout period of 2-4 weeks, the two groups switched their insulin delivery method. The participants were not restricted in their diet or daily activities.

The proportion of time spent at the target glucose concentration was 10.5 percentage points higher when using the closed-loop system. 76.2% of time was spent in the target range when using the closed-loop system, compared with 65.6% of the time when using the usual method. The closed-loop system reduced the amount of time spent with blood glucose levels under 3.5 mmol/L (hypoglycemia) by 65%.

93% of participants were satisfied with the closed-loop system. 69% said they spent less time managing their diabetes when using the closed-loop system. Skin irritation related to the sensor occurred in 4 participants (14%). 1 participant left the study because of technical issues with the closed-loop system. 

This study concluded that closed-loop insulin delivery systems increased time spent with glucose concentration in target range, and decreased time spent with low blood glucose.

This study investigated a very small number of participants over a short period of time. As such, the results may not apply to all patients. Several of the researchers had financial and professional connections to manufactures of insulin drugs and insulin delivery devices.

The first hybrid closed-loop system was approved by the US Food and Drug Administration (FDA) in September 2016. It is not yet commercially available. 

Discuss whether this method of insulin delivery is suitable for you with your physician.