Last Sunday was a beautiful day. The sky was completely blue and the sun was strong. I enjoyed the nice weather by meeting friends in the park to play a pickup game of ultimate Frisbee. I met everyone to play at 2 pm, right in the middle of the day. Because of the running and the potential to fall down (lay out), I always disconnect my pump when I play ultimate Frisbee. I left my pump underneath my bag on the sideline. There isn’t any shade on the field, so I figured that my pump would stay cool enough as long as it was out of direct sunlight. Later that night, I started to feel sick. I tested my blood sugar and I was shocked to see a very high reading- 481! It didn’t make any sense that I was so high, because I had taken plenty of insulin over the afternoon and I had covered dinner fully. All of the sudden, it dawned on me that my insulin was not working, and it must have overheated on the field. Insulin is a protein. Although it is a very stable substance, extreme heat or cold can cause the protein to denature, decreasing its activity. Below 36 degrees Fahrenheit, insulin can freeze, and above 46 degrees Fahrenheit, it can break down. Left in the sun, it is easy to see how the insulin in my pump overheated, which explains why it was not effective at controlling my blood sugar. Insulin manufacturers agree on a standard recommendation to avoid spoilage. Insulin can be kept safely in the refrigerator until its expiration date. After it has been opened, it can be stored in the refrigerator or at room temperature, defined between 59 degrees and 86 degrees Fahrenheit, for twenty-eight days. Do not use insulin if it is cloudy or has solid particles floating at the top or bottom. It is also a good idea to start a new bottle when there is less than about 10% of the insulin left in the old bottle. If you notice a lot of unexplained hyperglycemia or that it is difficult to determine your insulin doses, you should always double check your insulin itself. Make sure that it is not expired, it is still clear in color, and that it hasn’t been exposed to extreme temperature. If you have any doubts, throw the bottle away and open a new one. It is always better to be safe!