The Outcome Reduction with Initial Glargine Intervention trial 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, or insulin, or standard care -- no insulin -- over a median of 6.2 years.
Principal investigator Dr. Hertzel Gerstein and Dr. Salim Yusuf of McMaster University in Hamilton, Ontario, found no difference among the two groups in cardiovascular outcomes or in the development of any type of cancer, suggesting daily insulin injection to normalize glucose levels is not harmful 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, the researchers said.
Some previous research suggested a link between insulin use and an increased risk of heart attacks, strokes and several kinds of cancer, but none examined the long-term impacts of insulin use on serious cardiovascular outcomes and cancers in high-risk individuals, the researchers said.
The findings were presented at the American Diabetes Association's 72nd scientific sessions in Philadelphia.
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