MONDAY, June 11 (HealthDay News) -- Three studies should squelch fears that taking a form of insulin called insulin glargine (Lantus) increases the risk of cancer, researchers say.
Prior research had suggested an increase in cancer risk with Lantus, an injectable drug used to treat diabetes. "But, the worry we had that Lantos might be associated with cancer seems not to be the case, and people should continue using insulin," said Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York City, who wasn't involved in these studies.
Lantus is a long-acting insulin, meaning patients need only one shot a day, rather than multiple injections, and it's easy to use, Mezitis added.
People using glargine often have type 1 diabetes, a condition in which the body can't make insulin, which is needed to regulate the amount of sugar in the blood. People with type 2 diabetes, the form linked to being overweight and sedentary, may also take insulin if lifestyle and dietary changes don't control their blood-sugar levels.
In the United States, where obesity and type 2 diabetes are soaring, Mezitis said he expects to see many more insulin users in years to come.
In each study, researchers wanted to see if there was any connection between daily doses of insulin and cancer.
The results were scheduled for presentation Monday at a meeting of the American Diabetes Association in Philadelphia.
In one study, Laurel Habel, a research scientist at the Kaiser Permanente Northern California Division of Research, and colleagues looked at the risk of cancer among 115,000 patients taking either glargine or an intermediate-acting insulin called NPH. This is usually taken twice a day.
"We looked at prostate, breast and colon cancer and all cancers combined," Habel said. "We saw no evidence that there was any relationship between glargine and the risk of these cancers."
In addition, no risk of cancer was noted among patients who switched from another long-acting insulin to glargine or in people who started on glargine first, Habel said.
But, these findings are based on short-term use of the drugs -- median duration was less than 1.5 years -- and she said additional follow-up is needed to evaluate cancer risk over the long-term. Cancer can take years to decades to develop, Habel noted.
In another trial, researchers from the University of North Carolina (UNC) looked at the risk of cancer in more than 52,000 people taking glargine or NPH.
Over two years of follow-up, the researchers found no association between either form of insulin and the risk for any cancer.
The UNC team used data from the Northern European Study of Insulin and Cancer, which included more than 447,000 patients, and found no spike in cancer risk for glargine or any other insulin.
"There was absolutely no association at all between the risk of cancer and any form of insulin," researcher Peter Boyle, president of the International Prevention Research Institute in Lyon, France, said during a Monday press conference. The researchers had looked for risk of all cancers, plus risks for cancers of the breast, lung, pancreas, lung, colon and prostate.
"There was absolutely no causal association," he added.
In yet another study, Dr. Hertzel Gerstein, a professor of medicine at McMaster University in Hamilton, Ontario, Canada, and colleagues found no raised risk of cancer or heart disease in a study of insulin involving more than 12,500 participants.
"At the end of the day, the study showed that one injection of insulin a day had a neutral effect on heart attacks, strokes and deaths. In addition, it had no effect on other outcomes like cancers," Gerstein said.
No protective effects on cardiovascular health or cancer were seen from insulin either, according to the report, published in the June 11 online edition of the New England Journal of Medicine.
Data and conclusions presented at medical meetings should be considered preliminary until published in a peer-reviewed medical journal.
For more information on diabetes, visit the American Diabetes Association.