What's the story on the effect of coffee or caffeine on insulin levels?  I have read a lot of conflicting reports.  Some say coffee increases insulin levels & insulin resistance.  Others say it reduces the risk of diabetes.  Some refer to coffee, and others refer to caffeine.  Here are my questions.  

Is it coffee or caffeine that affects insulin levels?  
Does either coffee or caffeine have an adverse (or beneficial) effect on insulin levels?  

Thanks,
Marylee