Type 1 diabetes: causes, symptoms, testing and daily care

Type 1 diabetes is a lifelong condition. It can feel overwhelming at first, but understanding how it works is the first step toward living well with it. This article explains the basics using information from health agencies, so you know what to ask your doctor.

What is type 1 diabetes?

The NIDDK describes type 1 diabetes as an autoimmune disease. The immune system destroys the beta cells in the pancreas that make insulin. With little or no insulin, glucose cannot get into cells for energy, and blood sugar rises. People diagnosed with it have it for life, and most need daily insulin. The WHO notes that this type was once called insulin-dependent or juvenile-onset diabetes.

Who gets type 1 diabetes?

• It is more common in children and young adults, but it can appear at any age (NIDDK).
• Having a parent or sibling with type 1 diabetes raises the risk.
• Genes and environmental factors may trigger the immune attack. The NIDDK says researchers are still studying the causes, and the WHO says the cause and prevention are unknown.
• The NIDDK says that adults under 35 at a healthy weight are more likely to have type 1 than type 2.

Common symptoms

According to the NIDDK, symptoms include more frequent urination, intense thirst, constant hunger, blurred vision, tiredness, slow-healing sores, frequent infections and unexplained weight loss. They usually develop over days or weeks. The NHS says it usually starts in children and young adults and that symptoms usually appear over a few days or weeks.

How is it diagnosed?

• A clinician reviews symptoms, medical history and test results.
• Blood glucose tests, such as the random plasma glucose test, the fasting plasma glucose test and the A1C test, detect diabetes but do not tell the type, says the NIDDK.
• Autoantibody tests help show whether diabetes is type 1.
• If the type is unclear, a C-peptide test, which measures insulin production, or genetic testing may be used.
• The NIDDK describes latent autoimmune diabetes in adults (LADA) as a slower-developing form in which insulin may not be needed for several months.

The NHS says that at a GP surgery a finger-prick test checks blood glucose, and if type 1 is suspected the person will usually see a specialist the same day.

How is it treated?

A doctor and diabetes team decide the plan. The NIDDK describes these main parts:

• Daily insulin, given with syringes, insulin pens or insulin pumps.
• Blood glucose monitoring and matching insulin to food, activity and glucose levels.
• Devices such as glucose meters, continuous glucose monitors (CGMs), and artificial pancreas systems that link a CGM with an insulin pump.
• Healthy eating, physical activity and mental health support.

The NIDDK says pancreas or islet cell transplants can restore insulin production for some people but require lifelong medicines to suppress the immune system, and are not a cure.

Emergencies to know about

Two situations need prompt treatment, according to the NIDDK:

• Diabetic ketoacidosis (DKA): warning signs include extreme tiredness, trouble breathing, fruity-smelling breath, fainting from dehydration, and stomach pain, nausea or vomiting. In children, DKA can be the first sign of type 1 diabetes.
• Low blood sugar (hypoglycemia): some people do not feel their sugar dropping, which the NIDDK calls hypoglycemia unawareness. Untreated, it can lead to coma.

When to see a doctor

See a doctor promptly if you or your child has symptoms such as strong thirst, frequent urination and weight loss. The NHS advises getting an urgent GP appointment or calling NHS 111 if type 1 diabetes is suspected. After diagnosis, the NHS says feeling overwhelmed or anxious is common, and a specialist team and diabetes nurse help with support and teaching.

In an emergency, call your local emergency number (112 in India, 911 in the United States).

This article is for education only and does not replace your care team's advice.