Like vaccines, insulin can also be rendered useless if it is frozen. When insulin freezes, it forms crystals and clumps, and the molecular structure is changed, as is the potency of the insulin. Unlike vaccines, insulin can cope with higher temperatures – an unopened bottle of insulin typically lasts for around one week at room temperature. The advisable temperature range for storing insulin is the same as for storing vaccines; 2 to 8 degrees Celsius. These insulin fridges are specifically designed for storing insulin at the appropriate temperature.