In Type 1 diabetes the pancreas fails to produce insulin and insulin injections are required for life.
The cause of Type 1 is unknown but it is thought to be an auto-immune process. In effect, the body produces antibodies to the pancreas damaging it and preventing it producing insulin.
Type 1 only affects about 15% of all people with diabetes and usually starts below the age of 40.
It is always treated with insulin injections. There are many different types and regimens. If you are on insulin, you should discuss the most appropriate one for you with your care team.
The above is an extract from the DRWF Patient Information Leaflet What is Diabetes? v5.1, published September 2015 (reviewed within an 18 month period).