Short of a cure that involves a transplant or other unexpected breakthrough, the quest for the Holy Grail of diabetes management continues to be the creation of a continuous insulin delivery device integrated with a biosensor. The latest FDA-approved insulin pump (Animas IR 1200, November 2003) does not fulfill this role, but it can serve as a springboard to discuss the application of biomechanical technology to the treatment of diabetes.
The simple insulin pump, once the size of a backpack, has evolved over the years. The various models available are very advanced and use microprocessors that run sophisticated software. In addition, these newer pumps have been designed to accommodate the changing lifestyles of individuals as the choice of features has exploded. These devices have become an integral part of a well-designed and implemented disease management approach for the estimated 17 million people with diabetes in the U.S.
There are a number of manufacturers of insulin pumps. They include Animas, Medtronic (which recently purchased MiniMed), Deltec, Nipro, and Dana. Disetronic is no longer distributing in the U.S. due to an FDA order issued in July 2003. In April 2003, Roche acquired Disetronic; Roche plans to work with the FDA to allow distribution after the documentation and manufacturing issues are resolved. Comparisons of the various devices can be accessed online at:
Common to all currently available pumps is the ability to program a basal rate of insulin infusion. The insulin is not actually administered continuously, but is administered intermittently about every three minutes. All devices allow for bolus administration, which takes into account the amount and type of carbohydrates eaten or provides insulin to manage elevated blood glucose as a correction dose.
The bolus can be administered as a true bolus, or the pump can be programmed to administer the desired amount over a period of time, making it easier for grazing, or if the patient suffers gastroparesis, or has ingested a meal that is high in fat content. Most of the products can decrease the basal rate (temporary basal) to a lower rate for a few hours to accommodate changes in activity when basal insulin needs may vary. Adjusting the rate can be accomplished by using audible tones, making it easier for those with poor eyesight.
Most units have a download function so a member of the health care team can log the pump history and use this information to adjust therapy. These data include the amount and time of the insulin administration, as well as other data that are entered into the unit (such as blood sugars and alarms). All units now have tamper-resistant features to allow programming to be done by parents and prevent children from pressing buttons. Some pumps have multiple basal programs that allow users to vary basal settings based on various daily routines.
A user can set up two or more basal profiles to accommodate shift work, sick days, and weekend and weekday schedules with little effort. This avoids the need to reprogram the entire device every time there is a schedule change. All units have mechanisms to detect occlusion. There are differences between the units in sensitivity and the amount of time that must pass before a warning sound is issued, so look at this feature when you contract or approve a certain device.
Gone are the days when complex symbols were used; all devices currently use simple English instructions and all have backlighting for low-light situations. All units now come with software. Although updates are available on a periodic basis, the cost associated with the updates varies, and may affect contracting with the various manufacturers. All units are designed to use insulin analogues such as Humalog (insulin lispro rDNA origin) or Novolog (insulin aspart rDNA origin). Interestingly, only Novolog is approved by the FDA for use in insulin pumps although the other is commonly used.
There are some other variables that may come into play when choosing a pump, one being the non-volatile memory. If there is a battery failure, or static discharge, the pump's memory can be lost — including the programmed rates for basal administration. This can cause the unit to stop the infusion without setting off the alarm. Although this is not common, it could be a differentiating factor when choosing one pump over another.
Other potential pump features include the ability to enter the carbohydrate amount ingested based on the type of meal. With this feature, the pump can calculate and administer a bolus based upon the preprogrammed carbohydrate/insulin ratio. Other units can calculate the amount of insulin needed based on the carbohydrate load and the patient's blood sugar, which can be entered into the device. More complex calculations take into account the "on board insulin," that is, the insulin that has been administered recently .
There are several differentiating features that must be considered in picking an insulin pump. The newest entrant, the Animas product, allows for lower basal increments of 0.025 units --nearly twice that in older models. It also allows for a lower bolus amount of 0.05 units instead of the previous 0.10 units bolus dose. This difference is probably of little use in adults, but children or extremely insulin-sensitive patients may benefit by this added control. This device is the only insulin pump that uses either one AA lithium or alkaline battery. The lithium battery lasts much longer, but may be difficult to find in rural areas. The latest model resists water to 12 feet for 24 hours.
Managed care implications
Managed care has spent little time reviewing and comparing these devices. Most MCOs have a limited set of criteria that are used to screen appropriateness.
Managed care decision makers should be knowledgeable about currently available products for a variety of reasons, including:
In addition, MCOs may attempt to use the pharmacy management model by defining a "preferred device" based on features or rebate and price considerations. A "formulary approach" to medical products is a relatively unexplored territory for MCOs. Differentiating between the products will be key to determining which to prefer.
In summary, the use of pumps for the treatment of diabetes is predicted to become more of an issue to managed care medical and pharmacy directors. Predictably, better control can lead to fewer of the devastating complications of diabetes, including retinopathy, amputations, and end stage renal dialysis.
By utilizing an evidence-based, data-driven disease management program combined with appropriate identification of the proper patient and aggressive contracting with pump manufacturers, managed care can produce better outcomes using these devices in a subpopulation of its membership.
And we can buy some time for developments such as gene therapy or transplant technology — improvements that will be the topic of Tomorrow's Medicine.
Thomas Morrow, MD, is president of the National Association of Managed Care Physicians and vice president and medical director of Matria Health Care. He has 19 years of managed care experience at the payer or health plan level.