I am still reading about this but I "Think" caffeine stimulates the production of dopamine and adrenaline. Dopamine giving caffeine its addictive properties and Adrenaline causes the body to kick out glucose for energy.. causing the BS to spike..
I remember reading something like that. But in my testing I haven't noticed a bump. I was thinking that perhaps its because I have been drinking coffee for so long (since I was 10 years old), so my body doesn't kick out any glucose - as it expects me to drink my coffee while sitting at the computer.
Oh and I use half and half.