Diabetics on therapies such as Merck & Co's Januvia and Boehringer Ingelheim/Eli Lilly's Trajenta may find that these class of drugs can help them reduce the risk of developing autoimmune diseases.

That is the key conclusion of a study presented at the American College of Rheumatology meeting in San Diego looking at how often patients on dipeptidyl peptidase-4 (DPP-4) inhibitors) develop diseases such as rheumatoid arthritis, lupus, inflammatory bowel disease, psoriasis and multiple sclerosis compared to those not taking one.

Using data from US commercial insurance claims from 2005 to 2011, a team led by Seoyoung Kim of the  Brigham and Women’s Hospital in Boston compared two mutually exclusive groups: 58,275 patients with type 2 diabetes starting DPP-4 combination therapy with those on other combos. Patients taking insulin, or with pre-existing systemic autoimmune diseases, HIV or cancer were excluded.

Dr Kim told journalists at an ACR press briefing that although the overall incidence rate of RA or other autoimmune diseases was low (one in 1,000), patients taking DPP-4 combination therapy appeared to be 34% less likely to develop RA and 27% less likely to develop the other autoimmune diseases. A subgroup analysis comparing DPP-4 to sulfonylurea showed a similarly protective effect of DPP-4 on autoimmune diseases, but not comparing the drugs versus thiazolidinediones

Dr Kim acknowledged that the results are not definitive, but said that they may contribute to the understanding of new mechanistic pathways for preventing or delaying the onset of autoimmune diseases…could also lead to a potential new therapeutic approach". She added that future research is needed to determine the effect and safety of DPP-4 inhibitors in non-diabetics.

As well as Januvia (sitagliptin) and Trajenta (linagliptin), other approved agents in the class are AstraZeneca/Bristol-Myers Squibb's Onglyza (saxagliptin) and Novartis' Galvus (vildagliptin; not in the USA but Europe and elsewhere).