Do you find any difference contained by brands of insulin?

like Novalog and Humalog...BTW~ I use the pen for Novalog and my Dr wants to convert me to the same formula of Humalog (70/30 pens)Do you find any difference contained by brands of insulin?
There is a difference. Their chemical structure is slightly different.
Novolog works a touch more rapidly and for a moment or two longer than Humalog. In my experience it is also more stable - less coincidence of getting a "bad" vial or cartridge.
There isn't much difference between brands of insulin. It's only...insulin
It's different drug companies trying to make deeply the same product. Of course, they aren't exactly equal. For some Novalog may work better than Humalog and vice versa. Are you having problems near your Novalog? If you aren't I would be insistent with your doctor not to exchange. he probably likes Lilly's products better; that's why he requirements you to change, but if you are doing in good health, why change things?