The criteria for diagnosis are here – http://www.diabetes.org.uk/About_us/Our_Views/Care_recommendations/New_diagnostic_criteria_for_diabetes_/ basically a random blood sugar above 11, a fasting blood sugar above 7 or a blood sugar above 11 two hours after having 75g of glucose.
Some lifestyle advice would have been helpful, its much better (and cheaper) to take action early rather than wait until you need drugs. I know a lot of people find WeightWatchers good for this kind of thing – healthy eating, exercise, motivation etc.