Insulin (medicine)

What it means

Insulin is a hormone made by the pancreas that moves sugar from the blood into cells. People with type 1 diabetes need insulin to live, and many people with type 2 diabetes use it when other medicines are not enough.

Types differ by speed: rapid-acting insulin for meals and long-acting insulin for a steady background level. Some products combine long-acting insulin with a GLP-1 medicine in one pen.

Weight gain is common after starting insulin, partly because sugar that was lost in urine is now kept and stored. Low blood sugar is the main safety risk. When a GLP-1 medicine is added, prescribers often lower the insulin dose to reduce that risk.

Since 2020 the FDA regulates insulin as a biologic. That change opened the door to biosimilar insulins, some of which are approved as interchangeable with the brand they copy.

Why it matters

If you use insulin and start a GLP-1 medicine, your insulin dose may need to come down to avoid lows.