Repeated use of certain antibiotics may increase a person's risk for type 2 diabetes, a new study suggests.
Multiple courses increase risk
Researchers analysed data from one million people in the United Kingdom and found that those who were prescribed at least two courses of four types of antibiotics – penicillin, cephalosporins, quinolones and macrolides – were more likely to develop diabetes.
The risk of diabetes rose with the number of antibiotics prescribed, the findings showed. Two to five courses of a penicillin increased the risk of diabetes by 8 percent, while more than five courses increased the risk by 23 percent.
Two to five courses of quinolones increased the risk of diabetes by 15 percent, and more than five courses increased the risk by 37 percent, the study found.
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The higher risk of diabetes associated with the antibiotics was determined after adjusting for other diabetes risk factors such as obesity, smoking, heart disease and infections, the authors said.
The study was published in the European Journal of Endocrinology.
"While our study does not show cause and effect, we think changing levels and diversity of gut bacteria could explain the link between antibiotics and diabetes risk," study senior author Dr. Yu-Xiao Yang, of the University of Pennsylvania, said in a journal news release.
Antibiotics alter digestive ecosystem
According to lead author Dr. Ben Boursi, "gut bacteria have been suggested to influence the mechanisms behind obesity, insulin resistance [a precursor to diabetes] and diabetes in both animal and human models. Previous studies have shown that antibiotics can alter the digestive ecosystem."
Two other experts agreed that the findings are intriguing and warrant further study.
"It has been recognised for some time that bacteria in one part of the body can contribute to inflammation in another," said Dr. Gerald Bernstein, director of the Diabetes Management Programme at Mount Sinai Beth Israel Hospital in New York City.
Read: Symptoms of diabetes
He pointed to the connection between gingivitis – a bacterial infection of the mouth – and heart disease, as one example. So, linkages between alterations in bacteria in the gut and diabetes are not far-fetched, Bernstein said.
"This paper strengthened a potential hypothesis and we all have to wait and see what comes next," he said.
Dr. Spyros Mezitis is an endocrinologist at Lenox Hill Hospital in New York City. He agreed that "current research is showing that changes of composition of gut flora [microbes] is associated with chronic diseases including type 2 diabetes, cardiovascular and autoimmune diseases."
Unnecessary antibiotic treatments
For his part, Boursi added that "over-prescription of antibiotics is already a problem around the world as bacteria become increasingly resistant to their effects. Our findings are important, not only for understanding how diabetes may develop, but as a warning to reduce unnecessary antibiotic treatments that might do more harm than good."
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