NEW YORK (Reuters Health) - The effect of honey on blood sugar levels is the same no matter what its source, a new study shows. Tupelo, clover, buckwheat and cotton honeys had virtually identical glycemic indexes, Dr. Mark Kern and Jennifer Ilana Ischayek report.The glycemic index of a food is a measure of how quickly it causes blood sugar to rise. High carbohydrate, low fiber foods such as white bread or bananas have a high glycemic index, while high fiber foods containing complex carbs, including most vegetables, have a low glycemic index.