Repeated use of some types of antibiotic may raise the risk of developing type 2 diabetes, warn researchers.
Findings from a new US study underline the need to reduce unnecessary antibiotic prescriptions, it is claimed.
More than 3 million Britons are diagnosed with diabetes and nine out of ten have type 2 which occurs when the body gradually loses the ability to process blood sugar.
Type 2 is strongly linked to lifestyle factors such as being overweight or obese, leading a sedentary lifestyle and eating an unhealthy diet.
Researchers from the Departments of Gastroenterology and Medical Oncology at the University of Pennsylvania carried out the investigation.
They looked at the number of antibiotic prescriptions given to more than 200,000 diabetics in the UK at least one year before they were diagnosed with the disease, and compared this to the number given to 800,000 non-diabetic patients of the same age and sex.
They found that patients prescribed at least two courses of penicillins, cephalosporines, quinolones and macrolides were at higher risk of being diagnosed with type 2 diabetes.
The risk increased with the number of antibiotic courses prescribed, says a report in the European Journal of Endocrinology (must credit).
Patients prescribed 2-5 courses of penicillins – used for a variety of infections - increased their risk of diabetes by 8 per cent.
The risk increased by 23 per cent for those having more than five courses of penicillins.
Patients having 2-5 courses of quinolones, used in respiratory and urinary tract infections, had an increased diabetes risk of 15 per cent, which rose 37 per cent for those having more than five courses.
Study leader Dr Ben Boursi said ‘Gut bacteria have been suggested to influence the mechanisms behind obesity, insulin resistance and diabetes in both animal and human models.
‘Previous studies have shown that antibiotics can alter the digestive ecosystem.’
Senior author Dr Yu-Xiao Yang added: ‘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.’
There was no increase in risk associated with use of antivirals or anti-fungal medications and the study found little evidence of a link between antibiotic use and the risk of type 1 diabetes.