US engineers unveil implant for diabetics

A new glucose sensor implant could allow diabetics to monitor their blood sugar with a mobile phone and automatically adjust their insulin injections.

Bioengineers at the University of California, San Diego, and spin-out firm GlySens developed the sensor and wireless data system to continuously monitor tissue glucose and transmit the information to an external receiver.

Following year-long animal trials, details of which were published in the Science Translational Medicine journal this month, further human trials and FDA approval could see the device become an alternative to blood testing by finger sticking and needle-like glucose sensors that must be replaced weekly.

The sensor can function within the body without tissue forming on it for over 500 days. ‘That’s a big step from a scientific point of view, and it’s due to the sensor’s unique oxygen detection scheme,’ said UC San Diego bioengineering professor, David Gough.

Glucose and oxygen are drawn into the sensor, where they react in the presence of the enzyme glucose oxidase. The remaining oxygen is then measured and compared to the baseline oxygen recorded by another reference sensor.

The implant used in the pig study is about 1.5 inches in diameter, and 5/8 of an inch thick, and could be implanted in a simple outpatient procedure.

‘We hope to begin the first human trial within in a few months,’ said Gough. ‘If all goes well with the human clinical trials, we anticipate that in several years, this device could be purchased under prescription from a physician.’

The glucose information can be sent to a small receiving device, or potentially a mobile phone, and monitored by the patient or their carer.

The implant would provide constant monitoring instead of the four daily tests usually carried out by patients using finger sticking. This would allow patients to adjust their insulin injections, as well as diet and exercise schedules, and limit dangerous rises and falls in blood sugar levels.

‘We are moving toward something that will be automatic and quite unobtrusive,’ said Gough. ‘Others wouldn’t even know if someone is using a glucose sensor. Our goal is to get people off the finger stick cycle.’

Patients who use insulin pumps have to adjust them manually and to stick to a rigid schedule. The UC team aim to enable pumps to automatically adjust the rate of insulin administered based on readings from the sensor, effectively functioning like an artificial pancreatic beta cell.

‘If insulin pumps were programmed based on near-real-time readings from implanted glucose sensors, the pumps would adjust insulin dosing based on what your glucose number is after a meal. You wouldn’t have to be so rigorous about your schedule,’ said Gough.

‘With an insulin pump, there is always the concern that it will pump too much insulin, leading to dangerously low blood glucose levels. The sensor could serve as a safety mechanism against low blood glucose levels.’

Gough co-founded private firm GlySens to develop the sensor into its current form based on his research. He said the company has received a number of peer-reviewed grants from the National Institutes of Health in support of the project.