Type 2 diabetes is a massive health problem worldwide. About 29 million people, or 9% of all US adults, had type 2 diabetes in the year 2012. Interestingly, long-term studies have linked coffee drinking with a reduced risk of type 2 diabetes. Yet, oddly enough, many short-term studies have shown that coffee and caffeine can raise blood sugar and insulin levels. Why this happens is not fully known, but there are several theories.