Quick google search gave me this:
Caffeine can decrease insulin sensitivity in humans. Diabetes Care, 2002, Vol 25, Iss 2, pp 364-369. GB Keijzers, BE DeGalan, CJ Tack, P Smits. Smits P, Univ Nijmegen, Med Ctr, Dept Pharmacol Toxicol 233, POB 9101, NL-6500 HB Nijmegen, NETHERLANDS
Basically says both insulin and sugar rise higher with caffeine but it doesn't matter much if you aren't diabetic. Shouldn't take simple carbs with coffee apparently. However this begs the question, since insulin is good for bodybuilding wouldn't this actually be beneficial to the resistance-trained individual to drink coffee when taking complex carbs?