Insulin Pump Technology for Juvenile Diabetes Management

Understanding Juvenile Diabetes and Its Complications

Juvenile diabetes, also known as Type-1 diabetes, occurs when the body cannot produce insulin, which is necessary for the body to use sugar. Sugar is the basic fuel for the cells in the body, and insulin transports that sugar from the blood into the cells. Juvenile diabetes is a serious condition; however, with proper insulin management, it is possible for patients to live long, healthy, happy lives. There are currently between 750,000 and 1 million Americans who are dependent on insulin, with 30,000 new cases diagnosed each year.

Juvenile diabetes can be attributed to a number of conditions in the body, including hyperglycemia, hypoglycemia, ketoacidosis, and celiac disease. Some serious complications of juvenile diabetes are heart disease (cardiovascular disease), blindness (retinopathy), nerve damage (neuropathy), and kidney damage (nephropathy). Diabetes can also reduce blood circulation to the foot, which can result in severe complications and, in some cases, amputation.

Managing Blood Glucose: Monitoring and Insulin Therapy

In order to reduce the conditions and complications of diabetes, it is important to closely monitor the body's blood glucose level. The patient should strive to maintain a safe glucose level close to that of a non-diabetic. An A1C test provides a patient with information concerning his or her average blood glucose control for the previous two to three months, indicating how well their diabetes treatment plan is working.

There are a variety of products available to help monitor and regulate a person's glucose levels. Blood glucose meters and their supplies are an important part of glucose monitoring. Tests are also available which detect ketones, albumin, and glucose in the urine. Insulin can be administered with syringes, insulin pens, jet injectors, and insulin pumps.

A person with juvenile diabetes has very little or no endogenous insulin production, resulting in brittle glucose values ranging from very high levels to hypoglycemia. Diabetics need to strive to maintain a glucose level of HbA1c less than 6.5%, a fasting glucose below 100 mg/dL, postprandial glucose below 140 mg/dL, and the avoidance of hypoglycemia.

This is a complicated process which must be adjusted based on a person's glucose data. In order to maintain a correct glucose level, the person must monitor their blood glucose levels prior to meals and receive daily injections or use an insulin pump. The benefits of tight control, in terms of prevention of complications, are worth the effort, the risks, and the expense. Intensive insulin regimens should be available to all juvenile diabetics and should be the standard of care.

In the 1920s, Banting and Best revolutionized the treatment of diabetes with the extraction of insulin from animal pancreases. Supplemental insulin administration remains the treatment for insulin deficiency, which characterizes juvenile diabetes. While insulin therapy is important for maintaining glucose levels, there can be problems with the dosage and timing of insulin administration. Over the years, advances have been made in insulin therapy, such as the creation of the synthetic insulins lispro and aspart. These are short-acting insulins that are quickly absorbed from subcutaneous tissue and disappear more quickly, making it possible to give a dose much closer to mealtime than regular insulin, with less risk of hypoglycemia at a later time. It is also easier to give larger doses than with regular insulin, creating higher peaks to address postmeal glucose levels with less risk of hypoglycemia. Insulin pumps are able to use lispro and aspart insulins to efficiently maintain glucose levels.

There are different types of devices which can be used to infuse insulin into the body. These devices are classified as a closed or open loop system depending on whether they have a glucose sensor. They include: insulin pumps (open-loop); computer-controlled insulin pumps with a sensor (closed-loop); hydrogels — implanted artificial drug delivery systems providing chemical feedback between blood glucose and insulin release from a non-refillable reservoir of limited capacity (closed-loop); and transplantation of insulin-producing tissue (islets) and the bioartificial pancreas, which employs the natural beta cell for both glucose sensing and insulin delivery.

An insulin pump administers continuous subcutaneous infusion of insulin (CSII), permitting the programmed timing of insulin levels. These pumps allow preprogrammed delivery of basal insulin profiles as well as quick pre-meal infusion of bolus insulin doses. The insulin is pumped into the body via an indwelling subcutaneous catheter, which must be changed every 48 to 72 hours. Implanted pumps deliver insulin directly into the peritoneal cavity and then to the portal venous system, allowing a first pass through the liver before entering the peripheral circulation — similar to normal physiological pancreatic insulin. These catheters have a tendency to clog over time, and the need to change the internal catheter surgically on an annual or more frequent schedule has constituted an impediment to the wider distribution of implanted pumps.

History and Development of Insulin Pumps

The hope of ending continuous subcutaneous injections resulted in the development of insulin pumps. The initial pumps provided the possibility of maintaining correct blood glucose levels in juvenile diabetics. When the pumps were introduced over 20 years ago, they were cumbersome and not well received. However, the development of new, robust, and easily programmable insulin pumps has led to greater acceptance of this therapy by both physicians and patients.

The first insulin pump was approximately the size of a microwave oven and performed exactly the same functions that the beta cells perform in a non-diabetic pancreas. This device, the Biostater, measured blood glucose levels and dispensed insulin into the bloodstream every five minutes. Because of its size, it was used to treat diabetic ketoacidosis, as well as in diabetes-related research studies.

The portable insulin pump was first considered when Yale researchers explored the possibility of an individual monitoring their own glucose levels and adjusting the pump as needed. The first portable pump was originally one used for chemotherapy, since the concept was taken from the way cancer patients received their medicines. It weighed over a pound and used a large syringe placed on the outside of the pump. The early pump was about the size of an aerosol can — only wider and rectangular — with dials on the outside and blinking red LED lights. The pump delivered diluted regular insulin at a constant rate, and the user pumped in extra insulin based upon mealtimes and blood glucose levels.

Since the pumps were based on those used in chemotherapy, the manufacturers of chemotherapy pumps made the first pumps specifically designed for insulin. There were differences between the two: the insulin pumps were smaller and lighter, with the syringe mechanisms hidden in a covered compartment. These pumps were much thinner and sturdier, which gave them distinct advantages over the converted chemotherapy pumps. The pump was more cosmetically acceptable for the user and allowed the user to be more active, with less caution required to avoid damaging the pump during activities.

There was, however, a flaw in the initial pump: the user still had to dilute U-100 insulin into concentrations such as U-18 or U-36 with saline — and eventually with the same fluid in which insulin is dissolved. This was due to the fact that the pump design was based on how chemotherapy drugs were delivered and not on how hormones such as insulin are produced and used in the body.