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As a scientist who has type 1 diabetes, Dr. Kowalski knows that the cure may be a long time coming. But he's optimistic, nevertheless, because he believes that technology will revolutionize diabetes management long before the cure raises its shy little head.
As head of the Juvenile Diabetes Research Foundation's (JDRF) Strategic Research Projects, he's dead certain that continuous glucose monitoring is the wave of the future and that a closed-loop artificial pancreas is not far off.
It's a Tough Road
The readers of Diabetes Health know that diabetes is more than shots, more than pumps, and more than fingersticks. It's a 24-seven job, 365 days a year, and it's tough. My brother Steve was diagnosed with type 1 diabetes at the age of three in 1977. About seven years later, I too was diagnosed with type 1.
I understand how difficult it is to control diabetes. I believe, however, that new technologies have the potential to make it infinitely easier. The JDRF has recently launched a major initiative that aims to bring these new tools to reality, eventually including even the artificial pancreas.
The Teeter-Totter Ride of Glucose Management
The evidence is clear - lower A1cs mean fewer complications. High sugar levels lead to the devastating complications that we all fear. Yet most people with diabetes are not reaching recommended glucose control levels. Why, if insulin lowers blood sugar levels, are A1c targets not being met?
Diabetes is like a teeter-totter, a constant balancing act. While we all realize that a lower A1c will reduce our risk of long-term complications, the counterbalance is low blood sugar (hypoglycemia). People with type 1 diabetes suffer an average of two episodes of symptomatic hypoglycemia per week, and one severe, temporarily disabling episode per year.
Severe episodes can cause seizure, coma, and even death, and every episode reduces a person's ability to detect impending low blood sugar.
Even Nine Fingersticks Daily Isn't Enough for Good Control
Currently, we attempt this balancing act by monitoring blood sugar levels with fingersticks. While self-monitoring has advanced diabetes care tremendously, there is still much room for improvement.
A 2005 study by Dr. Bruce Bode illustrated the extent to which the fingerstick approach is inadequate. A group of 101 type 1 and type 2 patients who monitored glucose levels through frequent fingersticks (an average of nine per day) spent less than 30 percent of the time in the target glucose range of 90-130 mg/dl.
Over nine fingersticks a day and less than thirty percent of the day in target! To me, this speaks to the frustration of many in their search for the perfect A1c. Even with intense effort, it often seems out of reach.
CGMs Are the Moving Pictures of Glucose Monitoring
Continuous glucose monitors (CGMs), devices that provide continuous readings, offer hope for better A1c's than fingersticks. While fingerstick readings give just a number, CGMs show not only the level of glucose but, most importantly, whether it is rising and falling.
Many compare the shift from fingersticks to CGMs to the shift from still photography to moving pictures. Photographs can provide high resolution at little cost, but they are static. Videos show movement, but at higher cost and lower resolution. A continuous glucose monitor acts like a movie, while fingersticks are still photos.
A continuous glucose monitor can dramatically improve understanding of how glucose is trending throughout the day. A fingerstick reading of 85 mg/dl can mean different things depending on what is really happening to a person's blood sugar. For example, 85 and steady is right on target. 85 and rising is probably okay as well. However, 85 and dropping may mean that you are at risk for a low blood sugar event.
Real-time CGMs allow a patient to intervene by eating food or taking insulin to prevent blood sugar levels from going too high or too low. Real-time CGMs also can be programmed to sound an alarm for readings below or above a target range. An obvious use of this feature is to detect hypoglycemia during sleep, so that glucose can be quickly administered to prevent severe lows.
The Food and Drug Administration (FDA) has already approved two CGMs: the Guardian RT Continuous Glucose Monitoring System (Medtronic MiniMed) and the STS Continuous Glucose Monitoring System (DexCom). Another CGM, the Abbott Diabetes Care FreeStyle Navigator, is under review. All provide continuous real-time readings.
Studies Show Promise
Initial clinical studies suggest that the new generation of CGMs will be more effective. Data from studies of each of these devices show considerable promise. Patients spend more time in the target range, have lower A1c levels, and spend less time low.
However, many people question whether these devices are accurate enough. My answer is a resounding yes. The body of evidence continues to grow, and the JDRF has just launched the largest study to date examining the benefits of continuous glucose sensors.
Why Aren't We All Using CGMs?
Despite these encouraging results, a number of barriers remain before CGMs become a mainstream product. Currently approved CGMs are indicated for use as an adjunctive device to complement, not replace, standard home glucose monitoring devices. They differ from blood sugar meters in that they measure interstitial fluid glucose - the fluid between the cells in the body. Research is needed to determine if, and when, they can replace fingersticks.
Many people with diabetes will not be able to afford these devices unless public and private insurers provide reimbursement for them. In addition to trials that demonstrate improved health outcomes, data is needed to show that they provide cost savings, such as reduced A1c's, fewer trips to the emergency room, fewer missed days of work or school, fewer glucagon injections, and so on.
Closing the Loop: The Artificial Pancreas
In the near term, CGMs will enable people with diabetes to better manage their glucose levels. In the long term, the ultimate diabetes management device will be a closed-loop artificial pancreas that will monitor blood sugar levels and dispense insulin automatically.
Initially, the artificial pancreas will be an external device made up of three components: 1) an insulin pump, already widely used, 2) a continuous glucose monitor, and 3) an algorithm to link the two so they operate in a single "closed loop." Eventually, the artificial pancreas may be implanted subcutaneously.
A 2006 study by Dr. Stuart Weinzimer at the JDRF Hypoglycemia Center at Yale University tested a prototype closed loop system in five type 1 patients, ages 13-18, which suggested that a closed-loop system is feasible for use with children. Notably, nighttime control was outstanding and meal-time blood sugar rises were considerably lessened.
A challenge will be developing an algorithm that can anticipate and accommodate changes in blood sugars in a real-world setting, such as the rapid rise in glucose following meals or the drop in glucose levels overnight or following exercise. To produce an artificial pancreas for the commercial market, more studies are needed to clearly demonstrate that it's safe and that it keeps blood sugar levels closer to target than the currently used tools.
In March 2006, the FDA made the development of an artificial pancreas one of its "critical path opportunities" and a top-priority research project. By putting a closed-loop artificial pancreas on this list, the FDA in effect committed to promoting the public- and private-sector collaboration necessary to reach this goal. The JDRF also recently launched a major and many-faceted initiative, the JDRF Artificial Pancreas Project, which aims to speed artificial pancreas technologies to patients with type 1 diabetes.
The Dream is at Hand
Automated insulin delivery has been a dream for those with diabetes for many years. We are on the cusp of realizing this dream. I have used a CGM for the last eight months, and it's been the most significant improvement in my life with diabetes.
Preliminary tests of a completely closed-loop system that uses off-the-shelf components are extremely promising. It is an exciting time in diabetes research, and we expect many breakthroughs in the coming years. There are many hurdles on the way, but I believe through a coordinated effort we can get to an artificial pancreas, and the payoff will be immense for millions of people.
0 comments - Sep 18, 2007