Matrishka
Welcome to the board! You are doing great so far, awesome! My mom has diabetes too and it can get worse (as it did for her)... awesome that you've kept it at bay and it will only improve as you lose more weight I'm sure.
Depending on the type of webcam you have, it takes still pictures in different ways. if you have your manual of course that is the first place to look for the answer. Do you know which brand and model it is? Mine which is a logitech, has a button on top you can press (but the cam has to be active first) and it will take a snap from the button. There are just SO many models but as far as I know they will all take a still image, you just have to figure out how. Some have a little utility that comes with it, and it shows your preview image (the video image which would be broadcasted) - sometimes there's a 'take a picture' feature in there.
As far as exercise goes, you could look into perhaps Tai Chi as a starting point, and see how you do with that. They suggest Tai Chi is a great exercise for people with special situations like yours. You can probably borrow one from your local library and see if you like it before committing to buying one.
Welcome again to the board and nice to see you here!
~ Angie