Biosensors in Diabetes

By Sylvie Renaud, Bogdan Catargi, and Jochen Lang

NOTE: This is an overview of the entire article, which appeared in the May/June 2014 issue of the IEEE Pulse online magazine.
Click here to read the entire article.

New, innovative therapies are being brought to bear in the treatment of diabetes. In 2013, 380 million people worldwide had diabetes, and almost 600 million are expected to have it by 2023. Diabetes is the major cause of non-traumatic amputation and blindness in developed countries. It is also an expensive disease. In the United States, one in five healthcare dollars is spent on diabetes.

The burden of diabetes is not only financial. Intangible costs (pain, anxiety, inconvenience and generally low quality of life, etc.) also greatly impact the lives of diabetes patients and their families. The burden for these patients, their care providers, and national economies drives the search for novel treatments and therapies. This article discusses a recent approach involving continuous glucose monitoring (CGM). One remarkable proposal by Google is a biosensor implanted into contact lenses to determine tear glucose levels and then transmit the data to a pump in the patient’s body. This device circumvents the multiple daily blood tests and injections currently necessary with certain types of diabetes. It is unclear whether the diabetes problem will be solved by a contact lens, but the concept is intriguing.

The article outlines the two major types of diabetes: type 1, caused by the destruction of insulin-producing beta-cells in the pancreatic islets, and type 2 (the major form), caused by insufficient insulin release and reduced efficacy of the hormone. Type 2 is often found in older patients and a panel of lifestyle interventions and drug therapies are available as treatment. Conversely, type 1 diabetes surfaces earlier in life and requires hormone replacement therapy by insulin injections. Because insulin is extremely potent and can cause brain damage and death by hypoglycemia, glucose levels have to be controlled very precisely, requiring constant blood sampling. Fewer patients are afflicted with type 1 diabetes, however, some 80,000 children develop the disease each year and numbers are on the rise. Several different physiochemical methods have been explored for noninvasive approaches, but they lack specificity, have problems with miniaturization, or provoke major local reactions.

The first clinical CGM devices were used in hospitals in the 1970s, leading to the artificial pancreas – an implantable device measuring interstitial blood glucose that drives an insulin pump delivering the hormone via a subcutaneous needle. The first portable glucose monitors to display real-time values became available in 2006. Recent data suggest that these devices not only lift an awesome burden from patients, they also improve their long-term health. However, there are some drawbacks that beg the question – can the biosensor (the centerpiece of the artificial pancreas) be improved?

The article describes how researchers are developing the technology for two distinct lab-on-a- chip applications. The field is very active and considerable progress can be expected in the near future. It took over 50 years to develop glucose sensors adapted to therapy, revolutionizing diabetes care. Looking ahead, expertise gained in this field may also help neuroscience develop operational biosensors and artificial organ parts to provide relief for a number of inborn or traumatic pathologies. In any case, the diabetes field, with its longstanding and well organized scientific, medical, and patient communities, should be able to benefit from interdisciplinary work in biomedical engineering.

For more details on these new therapies, see the full article.