Tobacco is plant that has powerful effects on us. In addition to nicotine, there are other alkaloids such as nornicotine, anabasine, and anabaseine. The synergistic blending of all the chemically active parts of the plant contribute to the users experience. I have read that nicotine affects insulin, this can be good or bad like all things. For instance, tobacco users tend to have lower weight than nonsmokers, but it may not be a good choice for those with diabetes, or who are prediabetic. These influences on insulin may even be related to it's effects on dopamine, thereby contributing to it's more pleasurable effects. Like anything that has an ability to change the way we feel, we are responsible for using it wisely. If you are experiencing negative reactions you may be smoking more than is good for you. Smaller amounts, less inhaling, filters, building tolerance, and lower nicotine blends are all good ideas. I read something about folic acid and B12 supplementation being protective to the pancreas. Don't label nicotine as being something undesirable to you, it is more likely that the dose your are getting is too high for you. Try not to go past the point of feeling good. Some suggested non tobacco blends, but these usually contain many different plants all of which also have an unknown effect on you. I'd suggest trying to smoke tobacco the way Sablebrush52 does as he posted in this thread http://pipesmagazine.com/forums/topic/how-long-do-you-draw-for