Study Finds No Increased Heart, Cancer Risk from Daily Insulin Glargine Use
Daily insulin glargine injections, begun during the early stages of type 2 diabetes, neither increased nor reduced the risk of heart attacks, strokes, cancer or cardiovascular-related mortality, researchers found in the largest and longest study of its kind, released at the American Diabetes Association’s 72nd Scientific Sessions®.
The Outcome Reduction with Initial Glargine Intervention (ORIGIN) study randomized more than 12,500 people at high risk for, or in the early stages of, type 2 diabetes to either one daily injection of glargine (insulin) or standard care (no insulin), over a median of 6.2 years. Researchers found no difference among the two groups in cardiovascular outcomes or in the development of any type of cancer, suggesting that daily insulin injections to normalize glucose levels are not harmful when taken over long periods of time. Patients given insulin maintained glucose levels in the normal range (90-94 mg/dL) throughout the duration of the study.
Some previous studies have suggested a link between insulin use and an increased risk of heart attacks, strokes and several kinds of cancer. But none have examined the long-term impacts of insulin use on serious cardiovascular outcomes and cancers in high-risk individuals, or have followed such a large study population.
“People have been debating the question of whether there are adverse consequences to long-term insulin use for years,” said Principal Investigator Hertzel Gerstein, MD, McMaster University Department of Medicine in Ontario, who jointly led the trial with Salim Yusuf, MD, from the same institution. “This study provides the clearest answer yet to that question: No, there are not.”
The study did confirm the presence of two previously known side effects of insulin – hypoglycemia and modest weight gain. However, both of these were minor, with patients gaining an average of 3.5 pounds over the duration of the study and experiencing a low rate of hypoglycemia, on average just over one episode per participant per year.
“We now know what the risks are of taking insulin on a long-term basis, and they are low,” Gerstein said.
The study also examined whether daily insulin use in people at high risk for type 2 diabetes would prevent or slow progression of the disease. It found that those who had impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and were randomized to receive daily insulin injections had a 28 percent lower chance of developing type 2 diabetes over more than 6 years even after the injections were stopped, compared to those who were not given insulin.
“We believe this is because giving insulin to those with somewhat elevated glucose levels allows the pancreas to rest during this period, essentially helping it to work longer,” Gerstein said. However, he added, the durability of this effect for more than 3 months after stopping insulin remains unknown.
“ORIGIN’s findings should reassure patients and clinicians regarding the long-term health impact of using basal insulin therapy to target normoglycemia,” he said. “Ninety years after it was first used to treat diabetes we can say that when you need an effective glucose lowering drug, there is no reason to be concerned about undiscovered long-term risks of using basal insulin early in the course of diabetes.”
Finally, the study looked at whether giving daily doses of one-gram omega 3 fatty acid capsules to people with type 2 diabetes could help to prevent cardiac-related deaths. Researchers saw no effect on cardiovascular outcomes, good or bad.
“This is the first study to look specifically at the potential cardiovascular benefit of omega three fatty acids for people with diabetes or prediabetes,” said Jackie Bosch MSc, Associate Professor at McMaster University and Hamilton Health Sciences. “We saw no benefit or harm in taking the supplement.”
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