What Is Type 1 Diabetes?

Type 1 diabetes happens when the body stops making insulin.

Insulin is a hormone made by your pancreas. Its job is to let glucose — sugar from your food — move out of your blood and into your cells, where it is used for energy. Without insulin, glucose has nowhere to go. It builds up in the blood while your cells go hungry.

In Type 1 diabetes, the body's own immune system destroys the cells in the pancreas that make insulin. Once enough of those cells are gone, insulin production stops.

This is the crucial difference from Type 2 diabetes, where the body still makes insulin but cannot use it properly. In Type 1 there is no insulin to use, which is why almost everyone with Type 1 needs to take insulin every day, for life. It is not a treatment that can be swapped for tablets or diet.

It appears most often in children and young adults, but it can develop at any age. Symptoms usually come on quickly — over days or weeks rather than years.

Having a parent or sibling with Type 1 raises the chance of developing it, though most people diagnosed have no family history at all.

Managed well, Type 1 diabetes is compatible with an entirely normal life. What it asks for is a routine, and a good understanding of how insulin, food and activity fit together.