Making adjustments to dosage question

I'm taking 500 mgs of Metformina every morning and each morning blood sugar between 130 - 140. I'm told it should be 100 - 120 so should I take more Metformina, eat less, eat more frequently or what? I can't walk so I can't exercise.

Thanks - rev

Thanks. I'm already doing low carb and hi fat, medium beer and moderate whiskey but I don't understand why the sugar fluctuates (quite a lot sometimes) when I'm doing the right thing and the same thing every day. Maybe exercise is the variable but that's unlikely since I can't walk more than 200 meters in a day. I just don't understand. Maybe the prescription amount was the docs guess and I should be on more?