Like "The lows present a more immediate danger as they come on faster than diabetic ketoacidosis (DKA) which is due to high BG's. Over my years with diabetes, I wound up in the ER several times with serious lows, but others had to get me there because I was too far gone to even realize I needed help. We started carrying a glucagon kit and my husband learned how to administer that to bring my BG's up rapidly. If you are aware that your BG is dropping, make certain to eat a FAST ACTING glucose source to bring it back up. (Following the 15/15 rule James noted). Fast acting glucose can be regular soda, juice, raisins, glucose tabs or gels, Life savers, jelly beans, plain sugar in water will also work. Avoid anything like cakes, cookies, candy bars because they will not work as fast; the fats in them actually slow up the absorption of glucose into your system. I was also hospitalized once with DKA due to prolonged high BG"s. That is also life threatening but usually requires your BG"s to be uncontrollably high for a longer period of time. In my case, I had been away on vacation and battling a flu, treating it without realizing that the infection also caused my BG's to be higher over several days. It was early in my diagnosis, around 1978. Of course, the best approach is to avoid the extreme highs and lows if at all possible, but that is easier said than done."