The widely used diabetes drug metformin could be used in patients with chronic inflammatory conditions to reduce the side effects of steroids such as serious infections, a proof of concept trial suggests. 

In the phase II trial 53 patients with a range of chronic inflammatory conditions were given a median dose of 20 mg prednisolone plus metformin or placebo for 12 weeks. 

While no significant changes in the primary outcome of  visceral-to-subcutaneous fat area ratio were seen between the groups, patients taking metformin showed improvements in metabolic, bone, cardiovascular and inflammatory surrogate parameters.

Patients in the metformin group were also less likely to contract pneumonia (1 vs 7 events; p=0·01) or moderate-to-severe infections (2 vs 11; p=0·001), the researchers reported in their paper published in The Lancet Diabetes and Endocrinology.

Lead author Professor Márta Korbonits, Professor of Endocrinology at Barts and the London School of Medicine and Dentistry at Queen Mary, said the ‘strikingly positive’ findings suggested that a simple and immediately available intervention could improve the clinical status of patients on glucocorticoid treatment. 

“The results could have a huge impact on the large number of patients on long-term glucocorticoids, improving treatment-related complications and their cardiovascular prognosis,” she said.

In an accompanying comment, Martin Reincke from the Ludwig Maximilian University of Munich in Germany, said that the “stunning efficacy of metformin on these surrogate parameters might call for immediate action.”

“If metformin is capable of reversing the side-effects of glucocorticoids, why not prophylactically treat every patient exposed to excess glucocorticoids with this drug?” he asked. 

However, he pointed out the very small sample size and short duration of the trial meant that  a larger, phase III trial would be needed before any changes to clinical practice were made.