Hi Trulee
I can understand your fear of the insulin and weight gain if you have fought so hard to lose the weight and you also have heart trouble to contend with, but if insulin will give you a better overall control then I would consider it . You know how to keep a check on your weight now, so hopefully you will be fine and make the adjustments to counteract any slight weight gain.
I have found that there was weight gain with my Basal insulin (Lantus) I do Ultra Marathon so to be honest the comment about diet and exercise being the only thing to make a difference when you are on Insulin was not rue at all for me, also I have spoken to others about this and they found the same.
When my Basal increased even with the same amount of miles a week and intensity of training sessions AND the same strict training diet my weight would increase if the basal did. I eat clean, same things day in day out when training, I would find the pounds would go on with a Lantus increase, interestingly the bolus increase made no difference at all. The weight would also go on as fat not muscle and I would see this happen as the Lantus went up so would the weight gain...not a lot ,but enough for me to see it and notice it with my times/performance.
I have read a fair amount of anecdotal evidence about this with Basal/Lantus . Now, Levemir is supposed to have a much more stable effect on weight gain, if that is a problem for you. It is even documented that people who have swapped form Lantus to Levemir without trying have lost weight.
It may be worth discussing this with your HCP and going for this Basal as it may be better for you, it is all trial and error at first but if Insulin gives you a much better level of control to improve your oveall health then seriously think about it as an option as there are a lot of options out there with different insulins.
I hope some of this helps and wish you all the very best