Type 2 diabetes, in which the pancreas doesn't make enough insulin or the body doesn't use the hormone effectively, is typically controlled by diet and medication, but most people also end up needing insulin therapy to manage their blood sugar as the disease advances.
However, about a third of these patients have difficulty achieving optimal blood-sugar control with insulin injections, which they must administer several times a day. Poor blood-glucose management can lead to such complications as vision damage, cardiovascular disease and kidney failure.
Insulin pumps deliver continuous amounts of rapid- or short-acting insulin through a catheter placed under the skin, without the need for self-injection.
The 2010-2013 study involved 331 people, aged 30 to 75, with Type 2 diabetes in Canada, Europe, Israel, South Africa and the United States. Researchers randomly assigned roughly half the patients to receive treatment with insulin pumps, while the rest continued with multiple daily injections. Each therapy delivers both long-acting insulin (basal) and rapid-action insulin (bolus) taken near mealtimes.
Before being split into the two groups, all patients had gone through a two-month "run-in" period to optimize their blood-sugar control, "adjusting doses the best that we could," said Toronto endocrinologist Dr. Ronnie Aronson, a co-principal investigator of the OpT2mise trial published Thursday in the Lancet. Each group then followed their therapy regimen for six months.
"At the end of the six months, we found the blood sugar had improved significantly more in the group that was pumping as opposed to the group that had remained on multiple daily injections," Aronson said Wednesday. "And that difference was quite significant both from a statistical point of view and very meaningful from a clinical point of view."
The study found that 55 per cent of diabetics on an insulin pump were able to meet their blood-glucose target, compared to 28 per cent of those on daily injections.
"That's nearly twice as many," said Aronson, noting that "glycated hemoglobin" — the three-month average of blood-sugar readings — dipped by 1.1 per cent in the insulin-pump group versus 0.4 per cent among those injecting insulin.
"So there was a difference, or a benefit, of 0.7 (per cent), which in diabetes terms is enormous. And the pumping group was able to do it with less insulin. And that's really not been seen before. That's a very significant finding as well," he said.
"The main implication is that for patients with Type 2 diabetes who are already using insulin and struggling to achieve the optimal control of their blood sugars, using a pump may be a more effective way to improve their blood sugar, to improve their chance of getting to target levels and to do it with less insulin and in a safe way."
Doctors don't know why the device is more effective in controlling blood sugar for some people, but it may be that continuously pumped insulin is better absorbed and used more effectively by the body. Medication-dose compliance may also play a role, Aronson said.
"When you're using an insulin pump, you're definitely getting all of the prescribed insulin in a given day. When you have to remember to take three or four or five injections a day, it's possible that from time to time you may forget to take those injections.
"It's probably a combination of both."
Lead author Dr. Yves Reznik of the University of Caen Cote de Nacre Regional Hospital Center in Caen, France, agreed that pumps enhance insulin absorption and increase insulin sensitivity due to the drug's continuous delivery through the skin.
"Our findings open up a valuable new treatment option for those individuals failing on current injection regimens and may also provide improved convenience, reducing the burden of dose-tracking and scheduling, and decreasing insulin injection omissions," Reznik said in a statement.
The study was funded by Medtronic, which manufactures insulin pumps, but Aronson said the company was "entirely hands off. We had full independence. We were not interfered with or influenced."
In a Lancet commentary, Dr. Pratik Choudhary of King's College London said the study "provides a compelling case for the clinical effectiveness of insulin-pump treatment in Type 2 diabetes, suggesting that it can help improve glycemic control in this difficult to treat group of patients who are unable to achieve glucose control despite increasing doses of insulin."
"However, cost-effectiveness of pumps in different health-care systems will need to be evaluated," he writes.
In Canada, there are several models of insulin pumps made by different manufacturers. Their average price tag is about $7,000, which does not include the $250 monthly cost for supplies. The devices can be used by people with either Type 1 or Type 2 diabetes. Some private insurance plans will reimburse all or some of the cost. Several provincial health insurance plans also cover the cost of insulin pumps for certain groups of diabetics.
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