• Humulin can be left unrefrigerated at room temperature (86°F [30°C]) for up to 31 days.
• Humulin is the brand name for four different types of insulin, each with a different speed of effect and length of time they work for. These are Humulin R, Humulin N, Humulin 50:50 and Humulin 70:30.

Humulin is a brand name for insulin that is made by Eli Lilly and Company.

Insulin is a hormone that is produced naturally in our bodies. Its main role is to allow cells throughout the body to uptake glucose (sugar) and convert it into a form that can be used by these cells for energy. Without insulin, we cannot survive, and death from diabetes was a common occurrence until insulin was discovered in the early 1900s by Frederick Banting and Charles Best.

Humulin that is unopened and not currently being used should be stored in the refrigerator at 36°F to 46°F (2°C to 8°C), but not frozen.

Opened Humulin may be kept out of the refrigerator as long as it is kept as cool as possible (and definitely below 86°F [30°C]), away from heat and light, and used within 31 days.

If not used within 31 days, the vials/pens should be thrown away, even if they still contain some Humulin.

Do not use Humulin after its expiry date or if it has been frozen, stored above 86°F [30°C]), or kept out of the fridge for more than 31 days.

Once Humulin has been unrefrigerated, it should not be put back in the fridge again.

There are several different types of Humulin and each one has been made to last for a specific length of time, for example:

• Humulin R: Short-acting insulin
• Humulin N: Intermediate-acting insulin
• Humulin 50/50: A combination of 50% intermediate-acting insulin and 50% short-acting insulin
• Humulin 70/30: A combination of 70% intermediate-acting insulin and 30% short-acting insulin Humulin L and Humulin U have been discontinued.

Different insulins that work for different lengths of time are needed so that the natural release of insulin by the body in response to food is better replicated.