What is Type 1 Diabetes?
Type 1 diabetes (T1D) is an autoimmune disease in which your immune system, which is designed to fight infection, goes haywire and attacks the cells in the pancreas that make insulin. Insulin is a hormone required to get the sugar in your blood—glucose—into your cells, which then use glucose as fuel to provide energy. In T1D, the attack on insulin-producing cells, called beta cells, leads to your body being unable to make enough insulin. As a result, you will require insulin therapy to ensure that your cells can take up glucose.1 This is different than type 2 diabetes, in which the body either does not produce enough insulin or cannot use it effectively.
T1D is caused by a combination of genes and environmental factors such as viruses. It typically occurs in children and young adults, although it can appear at any age. Although having a parent or sibling with the disease increases your risk, 90% of people with T1D have no family history. Your risk is also higher if you have any other autoimmune conditions, such as celiac disease, Hashimoto’s disease, and others, or if these conditions run in your family.2–5
Early T1D
Over the past 20 years we’ve come to learn that T1D doesn’t suddenly appear out of nowhere. It could be simmering for months or even years before symptoms occur. This is called early-stage T1D, or presymptomatic T1D. In fact, we now know there are 3 stages of T1D:9
- Stage 1 is the start of T1D. The immune system has already begun attacking the insulin-producing beta cells, although there are no symptoms and blood sugar remains normal. You are in stage 1 if you test positive for 2 or more diabetes-related autoantibodies.
- Stage 2 includes those with 2 or more diabetes-related autoantibodies, but now your blood sugar levels are abnormal because you have fewer and fewer beta cells so your body is making less insulin. However, you still have no symptoms.
- Stage 3 is when you are diagnosed. By this time, there is significant beta cell loss, and you typically show the hallmark symptoms of T1D: frequent urination, excessive thirst, weight loss, and fatigue.
This is why early screening for the autoantibodies that show up before you have any symptoms of T1D is so important, particularly since today there is a medication that can slow the progression to stage 3. You’ll find more information on screening here
It’s important to know the symptoms of stage 3 T1D because early treatment is essential to avoid complications.
Symptoms of T1D include6:
- Increased thirst and urination
- Increased hunger
- Blurred vision
- Fatigue
- Unexplained weight loss
These symptoms can come on quite quickly and require immediate medical care. About 30% to 60% of the time, people develop a life-threatening condition called diabetic ketoacidosis (DKA). It occurs when your body doesn’t have enough insulin to allow blood sugar into your cells for use as energy. Instead, your liver breaks down muscle and fat for fuel, which produces acids called ketones. When too many ketones are produced too fast, they can build up to dangerous levels in your body.7
Symptoms of DKA include7:
- Fruity smelling breath
- Dry or flushed skin
- Nausea or vomiting
- Stomach pain
- Trouble breathing
- Trouble paying attention or feeling confused
An episode of DKA early in the disease can lead to8:
- More DKA events
- Severe low blood sugar
- A greater risk of death
- Longer hospital stays
- Higher levels of insulin required over time
- A shorter remission period (called a “honeymoon” period during which the pancreas still makes some insulin)
- Worse control of blood sugar over time
All of this increases the risk of diabetes-related complications such as heart disease, kidney disease, and eye diseases.8
References
- Atkinson MA, Mirmira RG. The pathogenic “symphony” in type 1 diabetes: a disorder of the immune system, β cells, and exocrine pancreas. Cell Metab. 2023;35:1500-1518.
- DiMeglio LA, Evans-Molina C, Oram RA. Type 1 diabetes. Lancet. 2018;391:2449-2462.
- Noble JA. Immunogenetics of type 1 diabetes: a comprehensive review. J Autoimmun. 2015;64:101-112.
- Pociot F, Lernmark Å. Genetic risk factors for type 1 diabetes. Lancet. 2016;387:2331-2339.
- Redondo MJ, Jeffrey J, Fain PR, et al. Concordance for islet autoimmunity among monozygotic twins. N Engl J Med. 2008;359:2849-2850.
- Katsarou A, Gudbjörnsdottir S, Rawshani A, et al. Type 1 diabetes mellitus. Nat Rev Dis Primers. 2017;3:17016.
- Centers for Disease Control and Prevention (CDC). Diabetic ketoacidosis. www.cdc.gov/diabetes/basics/diabetic-ketoacidosis.html
- Simmons KM, Sims EK. Screening and prevention of type 1 diabetes: where are we? J Clin Endocrinol Metab. 2023;108:3067-3079.
- TrialNet. Stages of type 1 diabetes https://www.trialnet.org/events-news/blog/type-1-diabetes-staging-classification-opens-door-intervention
