Note to visitors in 2009:
This is a very old blog post. For the most recent information about Januvia's impact on cancers of the lung, prostate, ovary and melanoma, please visit this page:
where you will find many links to journal research about the impact of DPP-4 and cancer in the section headed "Research Connecting DPP-4 and Cancer."
Below is the original post which was made on 3/25/2007:
Now that I've taken Januvia for a few months and had a chance to do some more research on it, a couple of issues have come up that are making me rethink whether it is wise to take it, even though I am getting such good results.
My experience with Slow Wound Healing
After I'd been taking Januvia for a few weeks I cut myself (not very seriously) while cooking. But it seemed to take forever for the wound to heal. At the same time I noticed that I was getting sore spots on my fingers where I was testing my blood sugar. This really was unusual. I'd been testing 6-8 times a day while on insulin and my fingers never hurt. Suddenly they were getting red and sore.
This raised the concern for me that the slight alterations to the immune system, and possibly other effects of DDP-4 were affecting healing. I posted about this on the Januvia blog at http://diabetes.blog.com and someone chimed in that they had also noticed slow wound healing which went away when they stopped the Januvia.
This could be a VERY serious concern, especially if you were to have surgery while taking this drug. I asked a surgeon about this when I was considering some elective surgery, and she told me that I'd have to ask my endocrinologist because she prescribed the drug. However, my endo knows only what is in the prescribing information, which doesn't mention any effect on the immune system except that Januvia makes some minor changes in white blood cell levels the importance of which is unknown. (How's that for avoiding the issue. Why isn't it known?)
The relevant data about how DPP-4 inhibition affects the immune system is hidden in scholarly studies of the effects of inhibiting DPP-4 which make it clear that DPP-4 inhibition does weaken immune response. I think, though my understanding of molecular biology isn't strong enough to be sure, that DPP-4 inhibition may have some effect on the process of healing itself.
If you've experienced any wound healing problems with Januvia, please contact me. Click on my profile and use the email address there, rather than posting a comment, if you want a reply.
Could Januvia Promote Cancer?Because suppressing DPP-4 weakens the immune system, I have another very serious concern about whether it might promote cancer. DPP4 is also suppressed by melanoma cells and prostate cancer cells, and it is speculated that this might be what allows these tumors to fend off the immune system cells that are supposed to kill them. Rats fed a very high dose of Januvia (60 times the normal amount) did develop liver cancer, though mice did not. This is not trivial and only a lot of time will reveal the impact of DPP4 suppression on people.
I have seen it argued that since Januvia turns down the immune system, it might be extremely useful for people with diabetes who have inflammatory conditions like artery disease, gum disease, arthritis, and of course, inflammation of the beta cells. This may be true. Since inflammation is supposed to be what leads to heart attacks, downregulation of inflammation in the arteries could be good. It's also true that inflammation in the beta cells may be part of what kills them in Type 2 diabetes. There are also some initial studies showing that DPP-4 inhibition helps with autoimmune rheumatoid arthritis. However, for those of us who do not have inflammatory conditions--as revealed by tests like CRP (C-Reactive Protein), SED rate, etc.-- turning down the immune system might allow the random cancer cells we all produce from time to time to avoid detection and destruction.
Since I'm a melanoma survivor, I'm NOT happy about electively suppressing the same enzyme DPP-4 that melanoma cells suppress.
In an ideal world, we could trust the drug companies to test these drugs in ways that would assure us we weren't going to wake up in ten years and find out that this wonder drug increased our chances of getting cancer ten times. But this is a pill that retails for $5 a pill, sold by a drug company that really needs some new blockbuster drugs to keep its billion dollar profits going. They hit the market first with their oral incretin hormone pill which gives them a huge sales advantage. How likely are they to study the possibility that their fancy new drug has a fatal side effect that takes ten years to develop? The longest test of Januvia lasted just shy of two years.
I'm thinking I might talk to my doctor about switching to Byetta now that I know that incretin drugs are very effective for me. Byetta does not suppress enzymes and shouldn't have any direct effect on the immune system. (But then there is the concern about creating antibodies since it's injected. There's always something . . .)
NEW INFORMATION ABOUT JANUVIA AND CANCER