I wish I could give up. I've tried everything from cold turkey to Zyban to vaping and nothing has worked. I've been a smoker for forty years and now I can't see a time when I could say 'I'm a non smoker' And yes, it can affect bg.
Champix worked for me - brilliant! I smoked for over 40 yrs, increasing amount over time. In the last few years up to 60 a day, particularly when I wasn't sleeping well so smoked a lot during nighttime, and during winter months when I couldn't get out to potter in the garden. I had no thought or intention to stop smoking, particularly after such a long time, and I enjoyed my smoke - but my GP referred me to the stop-smoking nurse. Despite my telling her that I had no intention of stopping smoking, the nurse persuaded me to try, and prescribed Champix. I did it, only to be polite, but still with no intention of giving up my ciggies! I started the programme, not expecting any result at all, and nobody was more surprised than me when after about a week, I didn't have a cigarette, prior to a review meeting with the nurse, and never had another. I stopped there and then, no problems, no craving, no withdrawal symptoms, nothing. I didn't even finish the course. It worked for me. May not work for anyone/everyone else - but is worth a try, if it suits you medically-speaking.
p.s. Forgot to say, that was just over 3 yrs ago & I haven't smoked since, nor ever wanted to. Though I did have some withdrawal symptoms-- a severe cough (I never coughed before when I smoked!), sore throat, and teeth sensitivity, that went on for about 2 years, & was not pleasant to say the least. OK now, so was worth it in the long run.