I asked my doctor the same question. He said that my weight loss might well be affected - but if I was replacing fat with muscle that could only be a good thing as I'd be decreasing my overall insulin resistance. So while weight loss is a good thing, it's really fat loss that's important, particularly circumferential fat loss.
He did warn me against weights though until I managed to get my BP reduced to near normal levels and not to do anaerobic exercise at the expense of the aerobic stuff i.e. if you're going to do it, do it as an extra and not as a replacement to what you're already doing.