Signs and symptoms of autoimmune type 1 diabetes

Autoimmune type 1 diabetes is a lifelong, complex condition that develops gradually and silently in the early stages, so you could have the condition without noticing any symptoms.^1-3

By the time symptoms do appear, the autoimmune attack is well underway, with most people having already lost 60–85% of their insulin-producing cells.⁴

The early stages of autoimmune type 1 diabetes (stage 1 / 2) are presymptomatic, while the later, clinical stage (stage 3) is symptomatic, with a quick start of symptoms within days to weeks.¹

Along with symptoms, autoimmune type 1 diabetes can result in a medical emergency called diabetic ketoacidosis (DKA) if not identified early.⁵

Screening can help identify people with presymptomatic autoimmune type 1 diabetes and prevent medical emergencies.5 Early detection also allows you to take control of your health journey and provides you with plenty of time to prepare for a life with autoimmune type 1 diabetes.⁶

Learn more about the screening process.

Common symptoms of autoimmune type 1 diabetes:

The body uses glucose from food and drinks as one of the main energy sources. Insulin helps the cells take up glucose from the bloodstream. The lack of insulin in type 1 diabetes means that the cells consume glucose less effectively, and as a consequence, the cells starve. You may notice this by feeling more hungry than usual.⁷

Several factors may contribute to fatigue and weakness in people with type 1 diabetes. Changing glucose levels, nerve pain, and sleep problems all contribute to exhaustion and can cause fatigue and muscle weakness.^8,9

Irregularly high blood glucose in people with type 1 diabetes can impact the fluid levels in the eyes, which can cause swelling and lead to blurry vision.¹⁰

Increased blood glucose levels also harm the body’s defence system against bacteria and viruses, making people with type 1 diabetes more likely to get infections.¹¹

In autoimmune type 1 diabetes, the kidneys produce more urine to try to clear the excess glucose from the body. This makes you urinate more frequently than usual. The loss of fluid then makes you more thirsty than usual.⁷

Unexplained weight loss is one of the most common symptoms of autoimmune type 1 diabetes. As the body cannot feed its cells with glucose sufficiently, the body breaks down fat for energy to compensate, leading to weight loss. Additionally, the levels of glucose in your urine are higher, so when you pee, you lose calories.⁷

Recognize the warning signs of autoimmune type 1 diabetes with the 4 Ts of type 1 diabetes:¹²

• Toilet: Going to the toilet more frequently than usual or bedwetting in previously dry children.
• Thirsty: Feeling unusually thirsty.
• Tired: Experiencing unexplained tiredness.
• Thinner: Losing weight unintentionally.

Red flag symptoms are those that require immediate medical attention. If you or your child experiences any symptoms of type 1 diabetes, talk to a medical professional immediately.^12,13

Red flag symptoms in autoimmune type 1 diabetes can be a sign of autoimmune type 1 diabetes complications, such as diabetic ketoacidosis (DKA).^12,13 Watch out for warning signs of these complications:^12,13

• a fruity-smelling breath similar to the smell of nail polish remover or drop sweets
• rapid breathing
• nausea or vomiting
• severe fatigue
• confusion

Learn more about the potential complications of type 1 diabetes.

Autoimmune type 1 diabetes can occur at any age, with symptoms slightly differing in children and adults.¹⁴ In children, the effects of autoimmune type 1 diabetes on the body include, for instance, bedwetting, irritability, and/or unusual behavior.¹² Whilst in adults, symptoms can be similar to those caused by type 2 diabetes, making the diagnosis more challenging.¹⁵

Autoimmune type 1 diabetes is a complex disease and can take years to develop before the first symptoms appear. The exact triggers of the condition are currently unknown, although a combination of genetic and environmental factors is thought to cause autoimmune type 1 diabetes.¹

Learn more about how autoimmune type 1 diabetes works

Autoimmune type 1 diabetes is a complex disease and can take years to develop before the first symptoms appear. The exact triggers of the condition are currently unknown, although a combination of genetic and environmental factors is thought to cause autoimmune type 1 diabetes.¹

Learn more about how autoimmune type 1 diabetes works

If you recognize autoimmune type 1 diabetes symptoms in yourself or your child, talk to a healthcare provider. Seek immediate medical help when you notice red flag symptoms.

Autoimmune type 1 diabetes is often first diagnosed following a medical emergency.12 This doesn’t need to be the case.

Early detection of autoimmune type 1 diabetes through screening can identify individuals with an increased chance of developing the condition before type 1 diabetes symptoms appear and provides a better way to be introduced to living with the condition than through a medical emergency.¹⁶

Some individuals with a family history of autoimmune type 1 diabetes or autoimmune diseases, such as celiac or thyroid disease, have an increased chance of developing autoimmune type 1 diabetes. For these people, screening is strongly recommended.¹⁶

Calculate your risk of autoimmune type 1 diabetes.

MAT-GLB-2503976 (v1.0) | Date of preparation: September 2025