Type 1 diabetes doesn’t develop overnight – it progresses through several stages before a person shows symptoms or requires insulin. Understanding these stages can help families recognize risk earlier, explore screening options, and take steps toward delay of the condition. Here’s a look at what happens from early detection to diagnosis.

What are the stages of type 1 diabetes?

Antibodies are proteins made by the immune system to fight infections. However, in autoimmune diseases, the immune system mistakenly makes antibodies that target normal cells or tissues. In type 1 diabetes, four main types of autoantibodies attack the insulin-producing islet cells in the pancreas. This process starts long before any symptoms appear. The more types of diabetes autoantibodies someone has, the higher their risk of developing T1D.

Experts now understand that type 1 diabetes develops over time through three main stages:

• Stage 1: The body has made two or more autoantibodies linked to type 1 diabetes, but blood sugar levels are still normal and there are no symptoms.
• Stage 2: Two or more autoantibodies are present, and blood sugar levels start to become slightly abnormal on tests, but there are still no symptoms.
• Stage 3: Blood sugar levels become much higher, and symptoms such as feeling very tired, thirsty, or needing to urinate often start to appear. This is when most people are diagnosed.

What happens during the early, symptom-free stages?

In the early stages, someone who is more likely to develop type 1 diabetes (because of their genes) may encounter an environmental trigger, such as a virus or another unknown factor, that sets off the immune system. The immune system then makes autoantibodies that mistakenly attack the insulin-producing cells in the pancreas. Over time, the pancreas can’t make enough insulin, and blood sugar levels begin to rise slowly. By the time a person reaches stage 3, about 70–80% of insulin-producing cells have already been lost.

How can type 1 diabetes be detected before symptoms appear?

Detecting type 1 diabetes early requires special blood tests:

• Autoantibody testing: Looks for specific antibodies that show the immune system is attacking the pancreas.
• Blood sugar testing: Measures blood sugar using tests like fasting glucose, an oral glucose tolerance test (OGTT), and Hemoglobin A1c (HbA1c). These tests can identify type 1 diabetes long before symptoms develop.

Who should consider autoantibody screening and when?

In the past, autoantibody testing was usually offered to people who had a close family member with type 1 diabetes, often as part of research studies. The test can be done at almost any age but screening works best when done in children between ages 2-4, 6-8 and 10-15. Recently, countries such as Germany, Italy, and Australia have started screening all children because 85-90% of people who develop type 1 diabetes don’t have a family history of it. Those who have other autoimmune conditions, such as celiac disease or thyroid disorders, are also at higher risk, and should consider screening.

Can early detection change the course of type 1 diabetes?

Yes, finding type 1 diabetes early can make a big difference. It can reduce the chance of developing serious complications like diabetic ketoacidosis (DKA) at diagnosis. It also gives families time to learn about diabetes, plan for care, and even take part in studies testing new ways to delay or prevent the disease.

Health Canada recently granted Notice of Compliance (market authorization) for teplizumab, a medication that modifies the immune system to slow down its attack on insulin-producing cells.  This new medication can delay the onset of stage 3 diabetes by approximately two years when given to people in stage 2. This is a major step forward in changing how we manage type 1 diabetes before symptoms appear. In addition, there are many other strategies being tested now to delay or prevent type 1 diabetes.

What are the signs that type 1 diabetes has progressed to to stage 3?

Two key health changes often signal a progression to the third stage of type 1 diabetes: Blood tests now meet the cutoff for a diabetes diagnosis.

1. Symptoms of high blood sugar appear, including fatigue, excessive thirst, frequent urination, and unexplained weight loss.
2. At this point, the body can no longer make enough insulin on its own, and insulin treatment is needed.

How is type 1 diabetes managed after diagnosis?

After diagnosis, the focus is on keeping blood sugar levels in a healthy range and preventing long-term complications. This usually involves:

• Frequent glucose checks, often using a continuous glucose monitor (CGM).
• Insulin therapy, given through multiple daily injections, an insulin pump, or an automated insulin delivery system.
• Regular checkups, including foot and eye exams, to monitor for complications.These tools and supports allow people with type 1 diabetes to live active, healthy lives.

There is growing recognition of the importance of detecting type 1 diabetes before symptoms develop. Identifying the condition early can prevent serious complications at diagnosis and allow families to prepare and connect with care teams. Just as importantly, new therapies are emerging that can slow or change the natural course of the disease, offering real hope for delaying the need for insulin and protecting the remaining insulin-producing cells. As awareness and access to screening continue to expand, early detection is becoming a key part of improving outcomes for people at risk of type 1 diabetes.