Getting a test meter - I use a Spirit Healthcare Tee 2 - so you can see for yourself what sort of levels you get to after eating.
If you are racking up numbers in the teens then cutting down on carbohydrates should sort that out - sugar and starch (Yes, those healthy starchy foods) all end up as something we can't really cope with.
Swapping the high carb foods such as anything made from grain, potatoes, high sugar fruits, and eating lower carb foods could have you back in normal numbers pretty swiftly if you are a boring ordinary type two.
It might take a while for your eyesight to settle down - don't change your glasses for a while, if you wear them, you might find that you can suddenly lose weight, but eating meat, fish, cheese, eggs and low carb foods should sort you out, with any luck. If you find that the Metformin does wicked things then you can try slow release, but I found that I did not need the tablets - after 5 weeks of Hell thinking that they were something essential.