Diabetic Retinopathy Treatment Care

I’ve had type 1 diabetes for about 4 month and am on insulin injections twice daily. The last couple of days my feet have been sore and today when i got up my feet and ankles were swollen as well as sore. Lastly, my toenails have become very thick, brittle and of a yellow colour. Can anyone give me any advice please.

My sister is 58, and she has been diagnosed with having diabetes for several years. She takes her insulin injections every day as prescribed. She is having extreme pain in her feet every day, she takes percocept but it has gotten to where that does not even help.
The physicians just keep telling her its a side effect of having diabetes. Can anyone tell me if you have ever heard of having such and what can be done about it . There is no sense in anyone being in so much pain…..Thank You ahead of time….

I either read or seen a commercial that said something about how you can tell if your getting diabetes by your feet, and how diabetics have problems with theirs. How can you tell?