Type 1 Diabetes Causes in Adulthood

Type 1 diabetes mellitus is an autoimmune disease in which the body stops making enough insulin. It is often diagnosed in children and young adults, which is why it used to be called juvenile diabetes.

But type 1 diabetes can develop at any age, including in adulthood. Type 2 diabetes is the more common form and occurs most often in middle-aged and older people, though it can also start in childhood.

Without enough insulin, glucose builds up in the blood. Over time, high blood glucose damages blood vessels and nerves and can harm the eyes, kidneys, heart and feet.

Normal Blood Sugar Level & How to Check the Blood Sugar?

A normal fasting blood glucose level is 99 mg/dL or below. A level of 100 to 125 mg/dL suggests prediabetes, and 126 mg/dL or above suggests diabetes.

Doctors diagnose diabetes with lab tests such as fasting plasma glucose, the A1C test or a random plasma glucose test. A finger-prick meter is used to monitor blood sugar, not to diagnose diabetes.

Age alone does not decide the type. Doctors may order autoantibody tests to tell type 1 from type 2, especially in adults.

There is no cure for type 1 diabetes. Early diagnosis and treatment can prevent emergencies such as diabetic ketoacidosis (DKA) and help prevent long-term complications.

Type 1 Diabetes Causes

Type 1 diabetes is an autoimmune disease in which the immune system destroys the beta cells of the pancreas. Beta cells are found in the islets of Langerhans and make the hormone insulin.

Insulin helps glucose move from the blood into your cells to be used for energy. After a meal, when blood glucose rises, the pancreas normally releases insulin to bring it back into range.

Without insulin, glucose stays in the blood. Researchers believe genes and factors in the environment trigger the immune attack in type 1 diabetes. Known risk factors include:

Having a parent or sibling with type 1 diabetes
Certain genes
Having other autoimmune diseases

Damage to the pancreas from pancreatitis or surgery to remove the pancreas (pancreatectomy) can also cause diabetes mellitus. That is a different type of diabetes, not autoimmune type 1.

In some adults, the immune attack is slow. This form, called latent autoimmune diabetes in adults (LADA), can look like type 2 diabetes at first, and some people do not need insulin for several months after diagnosis.

Symptoms of Type 1 Diabetes Mellitus

Type 1 diabetes mellitus may cause:

Increased thirst
Frequent urination
Increased hunger
Weight loss without trying
Blurred vision
Feeling very tired

Symptoms often appear over a few days or weeks. In some adults, they develop more slowly and can look like type 2 diabetes.

Nausea, vomiting, stomach pain, fruity-smelling breath or fast, deep breathing can be signs of DKA, which is a medical emergency.

Target Level of Blood Sugar for Diabetes Individuals

For many adults with diabetes, the NIDDK lists these general targets:

Before a meal: 80 to 130 mg/dL
About 2 hours after a meal starts: less than 180 mg/dL

Your own targets may differ. Ask your health care team what yours should be.

Treatment Plan for Type 1 Diabetes Mellitus

1- Insulin Therapy

People with type 1 diabetes need to take insulin every day to stay alive. It is given with a needle and syringe, an insulin pen or an insulin pump. Insulin is not available as a pill.

Your care team will teach you how to check your blood glucose and adjust insulin around meals and activity.

2- Healthy Eating and Activity

Healthy eating and regular physical activity help keep blood glucose in range and protect your heart. Learn how the carbohydrates you eat affect your blood glucose and your insulin needs.

Type 1 diabetes does not turn into type 2 diabetes. However, some people with type 1 diabetes also develop insulin resistance, especially with weight gain.

Complications of Type 1 Diabetes Mellitus

Over time, poorly controlled blood glucose can damage blood vessels and nerves. This can lead to eye disease (diabetic retinopathy), kidney disease (nephropathy) and damage to the nerves and cause neuropathy. Common complications include:

Kidney disease and kidney failure
Heart disease and stroke
Diabetic retinopathy
Neuropathy
Foot problems

Keeping blood glucose, blood pressure and cholesterol in your target ranges can prevent or delay many of these problems.

HP Thoughts: Gestational diabetes is a different type of diabetes that can develop during pregnancy. Read our guide to learn more: An Overview Of Gestational Diabetes.

This article is for general information. If you have symptoms of diabetes, see a doctor for testing and treatment.