Life-saving as it can be, antibiotic use may also leave you at higher risk of developing Type 2 diabetes, a new study in the Journal of Clinical Endocrinology & Metabolism suggests.

Analyzing the medical records of Danish citizens, the authors found that there was a small but real association between antibiotic use and the future development of Type 2 diabetes.

"In our research, we found people who have Type 2 diabetes used significantly more antibiotics up to 15 years prior to diagnosis compared to healthy controls," said study author Dr. Kristian Hallundbæk Mikkelsen, a staff member of Gentofte Hospital in Hellerup, Denmark, in a statement .

Over a twelve year period (2000 to 2012), the research team studied 170,504 people with diabetes (confirmed via a person being prescribed antidiabetic drugs), and compared them to 1.3 million people, matched on gender and birth year, without diabetes. Not only was there an association between antibiotic use and a later diabetes diagnosis, but the more prescriptions of antibiotics a person filled out, the greater their risk.

On average, the team found that 0.8 prescriptions for antibiotics were filled out per year by diabetics, compared to 0.5 prescriptions by healthy controls. Though there wasn’t a large difference seen among any individual antibiotic prescribed, the authors noticed a small increase in risk for those given narrow-spectrum and bactericidal antibiotics (the latter being antibiotics that directly kill rather than weaken bacteria).

The Danish study is only the latest to find a correlation between antibiotic use and diabetes, which the authors themselves note. This past March, a similar study of United Kingdom citizens published in the European Journal of Endocrinology found that repeated exposure to one of five popular antibiotic types (including penicillin) predicted an increase of “diabetic risk,” after adjustment for known risk factors like Body Mass Index, smoking history, and history of cardiovascular artery disease.

In both studies, the authors theorized that antibiotics may exacerbate the development of diabetes by disturbing the microbial communities inside our bodies (specifically the gut microbiota) which influence our metabolism and weight — obesity also being a risk factor of the condition. However, as the authors admit, there remains the very real chance the relationship between antibiotics and diabetes could be more complicated than that.

"Although we cannot infer causality from this study, the findings raise the possibility that antibiotics could raise the risk of Type 2 diabetes. Another equally compelling explanation may be that people develop Type 2 diabetes over the course of years and face a greater risk of infection during that time,” Mikkelsen said. Infections are known to be more common in prediabetics and diabetics than the healthy population.

Whether antibiotic use serves as a canary in the coal mine or is a legitimate risk factor for type 2 diabetes, the authors are hopeful that further research on the link between the two continues.

"Diabetes is one of the greatest challenges facing modern health care, with a globally increasing incidence" Mikkelsen said. "Further investigation into long-term effect of antibiotic use on sugar metabolism and gut bacteria composition could reveal valuable answers about how to address this public health crisis. Patterns in antibiotic use may offer an opportunity to prevent the development of the disease or to diagnose it early."

Source: Mikkelsen K, Knop F, Frost M, et al. Use of Antibiotics and Risk of Type 2 Diabetes: A Population-Based Case-Control Study. Journal of Clinical Endocrinology & Metabolism. 2015.