My knees hurt until I got sports supplements

I would hardly class myself as an athlete. In fact the very thought of it brings a smile to my face, so why am I researching sports supplements in a retail catalogue and comparing the benefits of differing brands? I will tell you why, because I walk my dog seven miles per day and often find I get a real drop in blood sugar which makes me shake and feel weak. I know I could pack a chocolate bar, but I am after something a little more sustainable containing complex carbs that can be released into my blood stream over an hour or two. Another reason would be the need for something for my aching knees