Insulin delivery systems enter new era
The method of delivering insulin to Type I diabetics is on the verge of major changes, but experts have widely differing viewpoints on the benefits of some systems and what the future holds for diabetics who depend on insulin for survival.
Diabetes Management asked four experts in the field of insulin delivery to share their viewpoints on the latest developments and to put on their wizards’ caps to help us take a look into the future of insulin delivery. They are:
• Gerald Bernstein, MD, president of the American Diabetes Association (ADA) and a practicing diabetologist in New York City.
• William Duckworth, MD, professor of medicine and biochemistry at the University of Nebraska Medical Center in Omaha and author of a study on implantable pumps.
• Alan Garber, MD, PhD, professor of medicine at Baylor University and chief of endocrinology, diabetes, and metabolism at The Methodist Hospital in Houston.
• Jay Skyler, MD, professor of medicine, pediatrics, and psychology at the University of Miami and author of a study on inhaled insulin.
INJECTIONS
All the experts interviewed agree that the days of the old bottle and syringe are gone, or should be.
But they’re not. Large numbers of American insulin-dependent diabetes mellitus (IDDM) patients still use what has become an outdated method in most parts of the world, even though insulin pens are easy to use and convenient since patients don’t have to carry around bottles and syringes and draw up dosages.
Most pens hold cartridges containing 150 to 300 units of insulin. The patients simply dial up the required dosage, screw on the needles, and inject themselves.
"It’s very simple," Bernstein says.
"They work really well," Skyler agrees.
But most experts are perplexed at the low level of pen usage in the United States. "It’s not being used like it should be," says Duckworth. "It’s the major source of insulin delivery in Europe." He theorizes that primary care physicians don’t know how useful the pen can be.
Other experts say managed care companies balk at paying for the slightly more expensive system.
Bernstein calls that effort at cost cutting "stupidity" on the part of managed care companies and cited an 88-year old patient who was "terrified of needles" but was denied coverage for the pen because she was not visually impaired.
PUMPS
The external insulin pump is, by far, the delivery method of choice among the experts interviewed. They universally cite the pump’s reliability and ease of operation.
Although CSII pumps have been in use for more than 15 years, enthusiasm for them has increased in the past few years since the publication of the Diabetic Control and Complications Trial, according to ADA literature.
Studies have shown pumps provide improved metabolic control, reduced hypoglycemia, and reduced long-term complication rates. The experts say they provide greater flexibility in lifestyle and more varied meal timing with increasingly rare problems as the quality of pumps improves. Drawbacks include subcutaneous abscesses, leaking tubing, and pump malfunction.
Current models are still the size of a cigarette pack, but that may not even be small enough, particularly for young women who tell Garber they find it unsightly at the beach or with midriff-baring tops.
Skyler notes that the current Miss America, Nicole Johnson, wears an external pump and has made diabetes awareness her campaign.
While external pumps may be easier and more convenient than any other product currently on the market, their biggest drawback, experts say, is that the pump is still an injection, and the subcutaneous needle must be re-sited every two days. In addition, the cost of pumps is high ($4,000 to $5,000) and sometimes their use requires a two-day hospitalization to evaluate and initiate therapy. Managed care companies frequently balk at this cost as well. However, Duckworth says, two insurance companies, Blue Cross and Mutual of Omaha, "are more amenable to bearing the cost because they know it will save them money in the long run."
Implanted pumps have proven to be fairly reliable although there are problems with obstructions. They are not in wide use, nor are they likely to be because of the high cost ($10,000 or more) and must be installed surgically in the abdomen under general anesthesia.
To Bernstein, pumps are desirable but not viable because of the cost. "If everybody can’t have it, it’s not a solution," he says.
Duckworth says external pumps are "by far the best method of glucose control " for Type I diabetics, but "they take knowledge and support to maintain." Without support, many patients "get discouraged and give up."
"If I were a Type I diabetic, I’d use the pump," Skyler adds.
In the future, perhaps researchers can marry a blood glucose monitor to either type of pump so they will continuously monitor blood sugar and dispense the necessary amount of insulin as it is needed, effectively creating an artificial pancreas, he says.
INHALERS
Inhaled insulin may or may not be the wave of the future, but that treatment definitely is not a panacea, the experts say.
All agree it is convenient and has a great appeal for patients who dislike self-injecting.
But the inhalers, which have not yet received U.S. Food and Drug Administration approval, can only be used for short-term insulin delivery, so Type I patients will still have to inject themselves.
And the inhalers are inefficient.
Garber notes the inhalers only utilize 10% of the insulin they dispense, so it is necessary to administer extraordinarily large doses.
"First, this has the potential to use up the world’s supply of insulin, and second, what happens to the 90% that is not absorbed? Garber asks. I haven’t seen a good answer yet."
In terms of insulin supply, his colleagues believe that is not a problem since new insulin factories are currently under construction in anticipation of increased demand. As far as the 90% of insulin that is not absorbed, they clearly don’t know what happens to it.
Duckworth says more efficient inhalers are now being developed that will ensure that 25% or more of the insulin dispensed will be absorbed.
Bernstein, admitting the inhaler is "tremendously wasteful," says he "suspects [the unused insulin] gets picked up by the bronchial mucosa and gets washed out."
Skyler suggests the excess quantity is exhaled.
Regardless of the method of excretion, the four agree, the insulin is short-acting, and there have been no adverse effects reported since tests have monitored patients for blood glucose spikes. Despite its disadvantages, Skyler predicts that five years from now, Type I diabetics who do not use insulin pumps will be using inhalers and injecting with a pen for longer-acting insulin.
THE CURE?
Great enthusiasm for the islet cell transplantation concept has been expressed by some experts as a possible way of curing diabetes.
Unfortunately, it is just a concept, says Duckworth, who worked for several years on a means of transplanting islet cells to encourage the body to once again produce insulin. "Our program spent $10 million to $20 million, and we finally gave it up. I do not believe the problems can be overcome without a true scientific breakthrough, a major discovery."
While he thinks the time line may be long, Skyler says, "I suspect islet cell replacement, either with beta islet transplants or cells made into beta cells or genetically engineered cells or some variant thereof, will in fact occur."
Bernstein says cell transplants are possible but probably far into the future. "The real question is: Can we inject insulin-producing cells safely into the body either encapsulated or freely and have them nestle someplace and have them serve as if there was a normal pancreas?"
Of course, there’s a caveat. "It’s there in animals, in humans it’s been done, but the difficulty is what do you have to do to the person to get it to work? That is still a big burden," Bernstein says.
Garber concludes for all the experts interviewed, " I think we’ll still be stuck with the disease for the foreseeable future."
For further information, contact: Gerald Bernstein at (212) 288-1538. Alan Garber at (713) 790-4749. Jay Skyler at (305) 243-6146. William Duckworth at (402) 559-6205.
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