Diabetes Type 1

Type 1 diabetes, which was once known as juvenile diabetes and insulin-dependent diabetes mellitus (IDDM), is a chronic autoimmune disease in which the immune system mistakenly attacks and destroys insulin-producing cells in the pancreas, called beta cells. Insulin is a hormone necessary for regulating blood sugar (glucose) levels in the body. Without enough insulin, glucose builds up in the bloodstream instead of being absorbed by cells for energy, leading to high blood sugar levels (hyperglycemia). High blood sugar is damaging to the major organs in the body (heart, blood vessels, nerves, eyes, and kidneys) and causes many of the symptoms and complications of diabetes.

Unlike type 2 diabetes, which is often associated with lifestyle factors such as obesity and lack of physical activity, type 1 diabetes is typically diagnosed in children, adolescents, or young adults, although it can develop at any age. The exact cause of type 1 diabetes is not fully understood, but it is believed to involve a combination of genetics and environmental triggers, such as viral infections or exposure to certain toxins.

Type 1 diabetes is less common than type 2 diabetes (T2DM)—about 5-10% of people with diabetes have type 1.

Type 1 diabetes often appears suddenly. Symptoms of diabetes may include:

• Unusual and excessive thirst

• Frequent urination
• Extreme hunger but also weight loss
• Nausea and vomiting
• Blurred vision
• Extreme fatigue and weakness
• Mood changes and irritability
• Bedwetting in children

In children, the symptoms of type 1 diabetes can be similar to flu-like symptoms.

The exact cause of type 1 diabetes is not known. It is thought to be caused by an autoimmune reaction (the body attacks itself by mistake). This reaction destroys or damages the insulin-producing (islet) cells in the pancreas. This process can go on for months or years before you notice any symptoms.

Other diabetes risk factors include:

• Genetic

• Exposure to viruses and other environmental factors

Only about 5% of people with diabetes have type 1. It affects males and females equally. You’re at higher risk of getting it if you:

• Are younger than 20

• Are white

• Have a family history of type 1 diabetes

If you have type 1 diabetes, your symptoms can suddenly appear, while in type 2 diabetes, they tend to occur more gradually, and sometimes there aren’t any signs or symptoms at all. Symptoms can sometimes occur after you have a viral illness. In some cases, you may develop diabetic ketoacidosis (DKA) before a type 1 diabetes diagnosis is made. DKA occurs when your blood sugar is dangerously high and your body cannot get nutrients into your cells because you are not producing insulin. Your body then begins to break down muscle and fat for energy, causing a build-up of ketones in your urine and blood. Symptoms of DKA may include a fruity odor on your breath, heavy, labored breathing, and vomiting. If left untreated, DKA can be life-threatening.

Endocrinologists, who are an important part of your healthcare team and specialize in treating hormone-related conditions, can help treat you if you have type 1 diabetes. If your child has type 1 diabetes, they’ll need to see a pediatric endocrinologist.

Your healthcare provider will typically test you for type 1 diabetes if you have clear symptoms of diabetes. They will commonly use a random plasma glucose (RPG) or fasting blood sugar test to diagnose type 1 diabetes.

For an RPG, it will not matter when the last time you ate. For this test, a blood sugar level of 200 mg/dL (11.1 mmol/L) or higher suggests diabetes. For a fasting blood sugar test, you will typically take it in the morning after not eating overnight. A blood sugar level of less than 100 mg/dL (5.6 mmol/L) is healthy. If it is between 100 to 125 mg/dL (5.6 to 6.9 mmol/L), this is considered prediabetes. If it is 126 mg/dL (7 mmol/L) or higher on two separate tests, you can be diagnosed with diabetes.

Your healthcare provider may also use a hemoglobin A1C blood test to determine how long you have had high blood glucose levels. While these tests may confirm a diagnosis of diabetes, they cannot identify which type you have. Your treatment will depend on the type of diabetes you have, so knowing whether it is type 1 or type 2 is extremely important.

Another test your healthcare provider may perform is to check your blood for certain autoantibodies. These are antibodies that can attack your healthy cells and tissues by mistake. Certain types of autoantibodies are common in type 1 diabetes but not in type 2.

If you have type 1 diabetes, you will need daily insulin injections to maintain your blood sugar levels within normal ranges. Other important aspects of your diabetes care may include:

• Eating a healthy, balanced diet to help regulate your blood sugar levels

• Counting carbohydrates (carbs) in the food and drinks you consume so you can give yourself the right doses of insulin

• Regular physical activity which helps your body use blood sugar more efficiently
• Checking your blood sugar levels throughout the day or using a continuous glucose monitor and learning to adjust your meals/snacks and insulin dose based on these levels.
• Regular hemoglobin A1C testing. This should be done at least twice a year but may be recommended more often if your blood sugar levels are consistently too high.

Most commonly, insulin is injected under your skin (subcutaneously) using an insulin pen, insulin pump, or syringe. Another type of insulin is a rapidly acting inhalation powder. Examples include:

Ultra-long-acting insulin (lasts 36 to 42 hours)

• Tresiba (insulin degludec)

• Toujeo Max Solostar (insulin glargine)

Long-acting insulin (lasts 24 hours)

• Levemir (insulin detemir)

• Lantus (insulin glargine)

Intermediate-acting insulin (lasts 12 hours)

• Novolin N (insulin NPH)

• Humulin N (insulin NPH)

Short-acting insulin

• Novolin R (insulin regular)

• Humulin R (insulin regular)

Rapid-acting insulin (lasts 2 to 4 hours)

• Apidra (insulin glulisine)

• Humalog (insulin lispro)

• Novolog (insulin aspart)

Rapid-acting inhalation powder (lasts 3 hours)

• Afrezza (insulin human)

It is important to monitor your blood sugar levels after taking insulin. Low blood sugar (hypoglycemia) can develop quickly if you are taking insulin. Symptoms typically appear if your blood sugar level falls below 70 mg/dL (3.9 mmol/L) and can include:

• Headache
• Irritability and nervousness
• Sweating
• Hunger
• Shaking
• Rapid heartbeat (palpitations)
• Weakness

Work with your healthcare provider so you have a plan to treat hypoglycemia if it occurs. This will usually include having juice, soda, glucose tablets, or another source of carbs and then rechecking your blood sugar levels after 15 minutes. If you have a severely low blood sugar, this may not work. Injectable glucagon is the best way to treat severely low blood sugar, but it is only available by prescription. Talk to your healthcare provider to see if you should have a glucagon kit and be sure you and your family members know when and how to use it.

Over time, high blood glucose can lead to serious complications if left untreated. These problems include:

• Heart disease
• Heart attack or stroke
• Kidney disease
• Eye problems such as diabetic retinopathy
• Dental disease
• Foot problems
• Nerve damage
• Sleep apnea
• Depression

You can delay or prevent these health problems by properly managing your blood sugar, cholesterol, and blood pressure, and by living a healthy lifestyle.

Resources

• What is Type 1 Diabetes? Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/what-is-type-1-diabetes.html. Accessed Mar. 19, 2024.
• Type 1 Diabetes. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/type-1-diabetes#diagnose. Accessed Mar. 19, 2024.
• Understanding Type 1 Diabetes. American Diabetes Association. https://diabetes.org/about-diabetes/type-1. Accessed Mar. 19, 2024
• ElSayed NA, Aleppo G, Aroda VR, et al. 2. Classification and diagnosis of diabetes: standards of care in diabetes-2023. Diabetes Care. 2023;46(Suppl 1):S19-S40. PMID: 36507649 pubmed.ncbi.nlm.nih.gov/36507649/. Accessed Mar. 19, 2024.