I take 60mg diamicron MR ( gliclizide) and have been on it over 20 years at the same dose , although doctors say that such a long time managing at that level is rare. This advice is based on my experiences so may or may not be most helpful for you
Re exercise - test before you plan to go exercising, if your sugars are lowish ( say under 5) then eat before you exercise. If they are 5-7 then Id say test part way through exercise and after - if they are low then eat. I was advised not to undertake exercise at blood sugar levels over 9.5 as the body can get confused and increase blood sugar because it cant take up enough into the muscle and thinks it needs more - not sure myself if thats true or not.
Some people say diamicron damages pancreatic cells, some say its the diabetes that does the damage - my thoughts are that uncontrolled diabetes does the most damage so use medication at the lowest level and for the shortest time you can alongside other strategies ( diet exercise etc) and stop taking them only if / when your body can achieve and sustain good blood sugars without them