What was the reason for stopping gliclazide?
So you go on to insulin and have odd glucose levels so the doc says take even more, different, insulin.........result, even more odd glucose levels.......?!
There's a myriad of things that could be causing erratic glucose levels - quick acting insulin timing, carb ratios, correction ratios, what you're eating, your liver, pancreas, your basal might not be right, you exercise regime.......
Start with a basal test, search on here there'll be a link or someone else may provide a link to the site that discusses how to do a proper basal test.
Best of luck.