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Symptoms and complications
It is important to be aware of the symptoms
of Type 1 Diabetes (T1D) as well as potential complications
Overview
T1D develops when the immune system gradually damages the cells in the pancreas that make insulin.1 As insulin levels fall, the body becomes less able to manage blood sugar, and symptoms begin to appear. For many people, these early changes happen quietly, with no clear symptoms at first.2
The most common symptoms and the easiest way to remember them are known as the 4Ts:5
- Toilet – needing to pee more often
- Thirsty – feeling very thirsty
- Tired – feeling more tired than usual
- Thinner – losing weight without trying
Not everyone will have all four symptoms, and having one symptom does not mean someone has diabetes.
Complications of T1D
T1D affects how the body controls sugar in the blood. When blood sugar is not kept within a healthy range, it can sometimes cause health problems. These problems do not happen to everyone, and good care can help reduce the risk.1
Short‑Term Health Problems
Sometimes, blood sugar levels can become:5,7
- Too high, which can make someone feel very thirsty or tired
- Too low, which can make someone feel shaky, weak, or dizzy
These changes can usually be managed with the right treatment and support from a healthcare team.
What Is Diabetic Ketoacidosis (DKA)?
If the body has very little insulin, it may start to make chemicals called ketones. When ketones build up, a person can become very unwell. This is called diabetic ketoacidosis, or DKA.3,4
The symptoms of DKA include but are not limited to:
- Being very thirsty
- Needing to wee more often
- Confusion
- Blurred Vision
- Feeling or being Sick4
Long‑Term Health Problems
Over many years, high blood sugar can affect different parts of the body, such as:
- the eyes
- the kidneys
- the heart
- the nerves
These problems do not happen straight away and do not affect everyone. With regular care, check‑ups, and support, many people with Type 1 Diabetes stay well and active.7
UK Emergency Support
If someone is experiencing symptoms that could indicate DKA or is feeling unwell with high blood glucose levels, they can:
- Seek urgent medical attention through NHS 111, their GP, or local urgent care services.
- Call 999 in an emergency situation.
These routes are part of standard NHS access pathways and do not replace clinical judgement.
What is Autoimmune Type 1 Diabetes?
Am I or my family at risk?
Can T1D be detected early?
If you are concerned about diabetes or its symptoms, please speak to your healthcare professional
References:
- Atkinson MA, Eisenbarth GS, Michels AW. Type 1 diabetes. Lancet. 2014;383(9911):69–82.
- Insel RA, Dunne JL, Atkinson MA, et al. Staging presymptomatic type 1 diabetes. Diabetes Care. 2015;38(10):1964–1974.
- Wolfsdorf JI, Glaser N, Agus M, et al. ISPAD Clinical Practice Consensus Guidelines: Diabetic ketoacidosis. Pediatr Diabetes. 2018;19(Suppl 27):155–177.
- Diabetes UK: What is DKA (Diabetic Ketoacidosis)? Accessed May 2026
- Diabetes UK: Type 1 Diabetes Symptoms. Accessed May 2026
- American Diabetes Association. Diagnosis and Classification of diabetes. Diabetes Care. 2025;48( 1):S27–S49.
- Diabetes UK - Complications of Diabetes - Accessed May 2026