What Are the Different Stages of Type 1 Diabetes?


While type 1 diabetes (T1D) makes up only between 5-10 percent of all diabetes cases, the diagnosis of the condition is actually easier to make for doctors than other types of diabetes, which can often go symptomless and develop more slowly—over months or even years. 

T1D is usually diagnosed due to the presence of classic symptoms of the condition—excessive thirst, frequent urination, weight loss and exhaustion. But did you know that once someone presents with symptoms of T1D, they’re already in stage three of the development of it? 

Here are the different stages of T1D and the benefits of detecting the condition sooner—for individuals and their families. 

The different stages of T1D 

T1D actually exists on a staged continuum, but by the time most people receive a diagnosis they are in stage three. 

The stages someone goes through before they are properly diagnosed can vary, but they are predictable.

Stage one 

Stage one is the first stage in the development of T1D and it is marked by the presence of β- cell autoimmunity and the detection of two or more islet autoantibodies

Islet autoantibodies are proteins developed by the immune system that are associated with T1D but not any other form of diabetes. These autoantibodies show an immune response to the islet cells of the body. 

Getting tested for these islet autoantibodies can easily be done by a simple blood test. 

The presence of two or more of the following islet autoantibodies is associated with T1D: 

  • Islet Cell Cytoplasmic Autoantibodies (ICA)
  • Glutamic Acid Decarboxylase Autoantibodies (GADA)
  • Insulinoma-Associated-2 Autoantibodies (IA-2A)
  • Insulin Autoantibodies (IAA)
  • Zinc Transporter-8 Autoantibodies (ZnT8A)

In this stage, there are no symptoms and people have completely normal blood sugar levels. 

Some people who develop T1D never develop detectable amounts of these autoantibodies, but this is a rare occurrence. Over 95 percent of people with new-onset T1D will have at least one islet autoantibody. 

The five-year and ten-year risks of developing T1D at this stage are 44 percent and 70 percent, respectively—the lifetime risk is near 100 percent. 

Stage two 

In stage two, people will experience slight glucose intolerance and higher blood sugar levels due to loss of functional β-cells—although most are still not experiencing symptoms at this stage. 

This is because blood sugar levels will still vary. The pancreas is still working, although not at 100 percent, and blood sugar levels are usually only slightly higher than normal. 

However, the five-year risk of developing T1D if you reach stage two is around 75 percent certainty, and the likelihood of developing T1D in your lifetime if you reach stage two is nearly 100 percent. 

Stage three 

This is the classic stage where most people receive their diagnosis. At this stage, people experience loss of β-cell functionality, resulting in both complete glucose intolerance and high blood sugar levels, often resulting in the classic symptoms of T1D, which include:

  • Frequent urination
  • Excessive thirst 
  • Exhaustion
  • Unexplained weight loss 

If diagnosis is not made promptly and treatment is delayed, stage three of T1D can quickly lead to diabetic ketoacidosis (DKA)—which can be fatal if not treated quickly. 

Shockingly, between 30-46 percent of all children diagnosed with T1D in the United States are in DKA at diagnosis, making it critical to see the signs early

The causes of T1D 

The exact cause of type 1 diabetes is still unknown. However, researchers believe it to be a combination of genetics, family history, and environmental triggers—like a virus

Likely the development of T1D is a combination of inherent risk factors from parents, genetic risk factors as well as an environmental trigger. 

When someone catches a virus, their immune system produces antibodies that fight off the infection. T-cells are in charge of releasing antibodies to fight off the virus. When someone develops T1D, the T-cells of their immune system mistakenly attack the body’s own β-cells instead of the viral particles, destroying their insulin-producing β-cells. 

One study showed that children exposed to enteroviruses are more likely to develop T1D, but it is not a guarantee that they will. 

Other factors may also increase the risk of T1D development, including: 

The importance of early detection 

If you are at high risk for developing T1D or have a family history of the condition, it is worth asking your doctor about autoantibody testing to see if you have the markers for the condition. 

This can be beneficial as the diagnosis can be made much more quickly if you test positive for autoantibodies, and you’re more likely to be diagnosed before you reach dangerously high blood sugar levels and life-threatening DKA. 

Additionally, new preventive medications are being released that have the potential to delay the onset of T1D. You may be able to postpone diagnosis altogether—at least for a few years. 

If you’re curious about getting tested, talk with your family to decide together if it’s right for you. If you decide to do so, you can learn more about getting tested at our screening resources.

Editorial Note: This content was made possible by Provention Bio, a Sanofi Company. Editorial control rests solely with Beyond Type 1.

WRITTEN BY Christine Fallabel, POSTED 09/25/23, UPDATED 10/30/23

Christine Fallabel has been living with type 1 diabetes since 2000. She's a health and science writer and has been featured in Diabetes Daily Grind, Insulin Nation, Diabetics Doing Things, and is a regular contributor to Diabetes Strong, T1D Exchange and Healthline. She earned her Master of Public Health from Temple University and received her Bachelor of Arts from The University of Delaware. In her spare time, she enjoys hiking with her husband in the mountains of Colorado, tinkering with her DIY Loop insulin pump, drinking strong coffee and reading in front of a cozy fire.