Long-term liraglutide use may increase blood sugar levels rather than lower them.
Published in the journal Cell Metabolism, the study reveals that over time, liraglutide (brand name Victoza) can exhaust insulin-producing beta cells in a way that leads to a rise in blood sugar levels.
The findings may have important implications for patients with type 2 diabetes, for whom liraglutide may be recommended if other medications have failed.
Approved by the US Food and Drug Administration (FDA) for the treatment of type 2 diabetes in 2010, liraglutide is a once-daily injection that is to be used alongside diet and exercise to help lower blood sugar levels.
Liraglutide belongs to a class of drugs known as incretin mimetics. It simulates the effects of an incretin called human-glucagon-like peptide-1 (GLP-1), which is a hormone expressed in pancreatic beta cells that increases the secretion of insulin.
According to the researchers of this latest study - including Per-Olof Berggren, PhD, of the Department of Molecular Medicine and Surgery at the Karolinska Institutet in Sweden - there is strong evidence that liraglutide is effective for type 2 diabetes, with studies showing that it leads to an initial reduction in blood sugar.
However, Prof. Berggren and colleagues note that few studies have investigated the long-term effects of incretin therapy.
Liraglutide reduced insulin secretion in mice over time
To address this research gap, the team analyzed the effects of liraglutide in mice that had been transplanted with human insulin-producing beta cells in the anterior chamber of the eye.
For 250 days, the mice were given a daily dose of liraglutide, and the team monitored how the drug affected the transplanted beta cells.
As found in previous research, the team identified an initial improvement in the insulin-producing beta cells. Over time, however, the drug appeared to exhaust the beta cells, leading to a reduction in insulin secretion that may cause a rise in blood sugar.
The researchers say their study has made an "important discovery," and they believe the findings are of significant value to clinicians, patients and the pharmaceutical industry.
Prof. Berggren says:
"We [...] need to take these results into account before prescribing blood-sugar suppressing GLP-1 analogues when planning long-term treatment regimens for patients.
Our study also shows in general how to carry out in vivo studies of the long-term effects of drugs on human insulin-producing cells, which should be extremely important to the drug industry."
Last month, Medical News Today reported on a study suggesting that sleeping in at the weekend may lower the risk of type 2 diabetes.