plateauing is so discouraging.. 
but if you keep doing it right... it will happen... from things I read... your body gets used to doing the same repetitive thing and it adjusts to it and lessens the effect... they talk alot about mixing up your exercise these days... keep changing it up so your body has to react to something new instead of adjusting to the same old same old....They often mention short bursts of hard exercise is better than long slower exercise, but that would have to be under strict supervision in many cases I imagine if you weren't already fit.
I watched this program the other night... really interesting... worth 18 minutes of your time... link to Catalyst program on Sugar... (I hope it works in your area, I often get US links that won't play out here)... I know you won't be having sugar being diabetic... but this might be a good explanation how you got there in the first place and help identify things with perhaps hidden sugar you didn't realise.
I know when I go right off sugar and just have two pieces of fruit a day, the sugar craving wears off and I have loads more energy.
Interestingly the doctor said exercise really only makes you hungry... not effective for weightloss... but good for keeping fit... you also need to be careful how much you are stressing your joints, your knees and hips need looking after too...
I remember a long time ago joining a local gym that opened up near me, I did 20 mins in the weight room and 50 mins aerobics 5 mornings a week after dropping my son to school.... over the course of a year I did not change weight at all... but I was the fittest I had ever been. I hadn't changed my diet at all. The doctor is quite right, it's good to keep healthy... but doesn't aid weight loss. However, if you do weights and build up muscle... the very presence of the added muscle burns calories on it's own. You shouldn't do weight work every day on the same muscles though... your muscles need time to repair... a day off in between or do different muscle groups on different days... and again, with the body getting used to your regime... mix it up every 3 months or so...
A good trick is to divide up your meals during the day to eat small amounts often... not going more than 3 hours without having something... handful of nuts, half a piece of fruit... something like that... to keep your metabolism working... apparently just doing this can cause the extra burning of calories just on it's own...without exercise being involved... every little bit helps..
Drinking 2 litres of water a day really helps with weight loss as well... if your body stores water... it helps flush it through...and you'll burn calories heading to the loo regularly.... lol 
keep your salt intake low too...
Keep the faith.... you already have the prime thing you need for success.... mindset...all else will follow... 
