A study that analyzed over 3,400 French adults over a period of 14 years found that those with Type 2 diabetes who received insulin treatment had a significantly increased risk of death.
According to Dr. Emilie Bérard, an epidemiology researcher at the University Hospital Center in Toulouse, France, patients with diabetes who were “treated with insulin at baseline were at increased risk of all-cause mortality.” Dr. Bérard spoke at the yearly meeting of the European Society of Cardiology, adding that the data “provides further information to the debate on the risks and benefits of increasing hypoglycemic treatments.”
The study adjusted for factors that may have affected the outcomes of the data. Even after the adjustments were made, the study found that diabetics who received treatment with insulin were five times more likely to die over the 14 year period of the study than the study participants who did not have diabetes. Those who received insulin were also 1.5 to 2.2 times more likely to die than diabetics who were treated with other hypoglycemic drugs such as metformin or sulfonylurea. The relative risk of death for diabetic patients who were treated with insulin was nearly double that of diabetic patients who did not recieve any treatment at all — the latter group was about 2.8 times more likely to suffer death than patients without diabetes.
Dr. Lars Rydén, a professor of medicine at the Uppsala University in Sweden, cautioned against taking the study’s findings at face value. The study was “on the right track,” according to Dr. Rydén, but its findings must also “be taken with a grain of salt.”
“The results indicate something, but we need further studies,” continued Dr. Rydén. He commented that a major potential flaw in Dr. Bérard’s findings were that it used several adjusting factors in a fairly small sample group of only 171 diabetic patients. “I think [the analysis] is on the edge of controlling for too many things in a small number of people, which led to extremely wide confidence intervals,” said Dr. Rydén.
The findings were also questioned because the participants did not undergo an evaluation of their A1c levels when the study began in 1995 and 1996. According to Dr. Bérard, this means that the adjusted analysis could not account for the varying quality of diabetes control that the patients may have received at baseline. Dr. Bérard speculated that the insulin treatment could have caused a higher rate of hypoglycemia which lead to a higher mortality rate, it could have caused increased weight gain, or it could be indicative of more serious cases of diabetes. It may have also stimulated the sympathetic nervous system, which could have promoted atherosclerosis and triggered vasoconstriction.
The study analyzed data collected from a random sample of 3,403 French adults who were aged between 34 and 64. The study began in 1995 and 1996 and was a part of the MONICA (Multinational Monitoring of Trends and Developments in Cardiovascular Disease) project, a large study sponsored by the World Health Organization. Of the study sample group, 171 participants had diabetes, with 123 on a hypoglycemic regimen and 48 who were not being treated for diabetes at all.
Dr. Bérard’s team analyzed the participants’ data 14 years after their first assessment and found that the mortality rates varied widely, from 7% in the group without diabetes to 33% in the group who were treated with insulin; those who were not receiving hypoglycemic treatment at the beginning of the study had a 23% mortality rate.