Diabetes type 2 and Letrozole

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My GP recently contacted me - after my annual diabetes check - because my results had rocketed from 63 to 89 and I have since had my metformin dosage quadrupled!!!

This is the second time tthis has happened. The first was around the the time I stared taking Anastrozole  - later changed to Letrozole - and I was contacted by my GP as an emergency. Through diet and a low dose of Metformin I was able to get my diabetes under control again but now this..

However, as my diet or lifestyle hasn't radically altered, I am wondering whether the adjuvant therapy I have been undergoing is the cause?

I found some Israeli research indicating that women taking Letrozole were slightly more likely to develop Type 2 diabetes after starting treatment with Letrozole but can't find anything about its effect on people with existing diabetes.

Although my treatment was excellent, in retrospect, I did find it a little odd that my diabetes was never discussed with me by the oncologist.

I'll deal with this. However, I am intrigued as to why there seems to be  little or no reference to the impact - if any - of hormone therapy on diabetes? Or chemotherapy overall? 

  • FormerMember
    FormerMember

    Thank you for this. I went to optician today who said my eyes are worse since this time last year and since finishing chemo…vision is definitely down requiring yet another set of driving/reading glasses. She casually stated “you may have diabetes but get checked out”. Also asked what meds I’m on and of course I said  Letrozole.  Will make app with GP soonest to get this checked. You could always speak to Macmillan Navigators to discuss why this wasn’t included as important, throughout your treatment. I wish you well..x

  • Hi, I am also type 2 diabetic and it has always been very stable and well controlled with metformin.  I had lung cancer in 2021 and had no problems with my diabetes but in 2022 I was diagnosed with breast cancer.  No one mentioned to me that the diabetes and breast cancer could be an issue.  However, it has been and I only found out by default at the GPs.  I am really struggling to get control over my blood sugars, they are just all over the place.  I was incorrectly put on Letrozole (I am lactose intolerant) so it made me quite ill.  I am now on Exemestane but same problem with blood sugars.  I have been put on additional meds for diabetes to try and help but so far not consistent.  I find it quite worrying and when I mentioned to my oncology nurse she didnt make anything of it just said, yeah it can be a problem.  from research, it appears well known that the hormone treatment can well and truly interfere with diabetes.