The purpose of INNODIA DETECT is to identify people who are at increased risk of developing T1D. Investigators are doing this by testing for markers in the blood (autoantibodies) that tell them an individuals risk of getting T1D in the future. What is Type 1 Diabetes (T1D)? T1D is a serious disease where the blood glucose (sugar) level is too high because the body cannot make a hormone called insulin. This happens when the body's immune system attacks the cells in the pancreas that make insulin (called beta cells), meaning that insulin production stops. This is harmful to the body as insulin does an essential job. It allows the glucose in the blood to enter cells and fuel the body, resulting in a lowering of the blood glucose level. What are Autoantibodies? T1D autoantibodies are markers found in the blood that indicate that the destruction of insulin producing cells has begun. The risk of developing T1D increases with the number of autoantibodies detected. People who have 1 autoantibody detected in their blood are at increased risk of developing T1D. The presence of 2 or more autoantibodies indicates that T1D is present but the individual does not show any signs or symptoms yet. However, these autoantibodies can be present for many years before someone develops symptoms of T1D. They often appear in the first few years of life. The investigators are asking children and adults across Europe, aged between 1 and 45 years, who have either a family member (parent, child, full or half sibling) or close friend diagnosed with T1D before 45 years of age to provided a small blood sample so they can look at these T1D autoantibodies. If a participant's autoantibody results are negative, this means they do not have autoantibodies and are at low risk of developing T1D. No further tests will be required, and they will exit the program. If results indicate a participant has 1 or more positive T1D autoantibodies, a member of the clinical team will contact and invite them to the hospital for a venous blood sample to confirm the result. This confirmation test will be done as part of routine clinical care by the participants clinical team. INNODIA DETECT will end here and, if confirmed positive, the participant will be invited to attend further follow-up by entering in a separate protocol (named INNODIA MONITOR).