Type 1 diabetes is a lifelong (chronic) disease in which there is a high level of sugar (glucose) in the blood.
Insulin-dependent diabetes; Juvenile onset diabetes; Diabetes - type 1
Type 1 diabetes can occur at any age. It is most often diagnosed in children, adolescents, or young adults.
Insulin is a hormone produced in the pancreas by special cells called beta cells. The pancreas is behind the stomach. Insulin is needed to move blood sugar (glucose) into cells. There, it is stored and later used for energy. With type 1 diabetes, beta cells produce little or no insulin.
Without enough insulin, glucose builds up in the bloodstream instead of going into the cells. The body is unable to use this glucose for energy. This leads to the symptoms of type 1 diabetes.
The exact cause of type 1 diabetes is unknown. Most likely it is an autoimmune disorder. This is a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. With type 1 diabetes, an infection or another trigger causes the body to mistakenly attack the cells in the pancreas that make insulin. Type 1 diabetes can be passed down through families.
High Blood Sugar
The following symptoms may be the first signs of type 1 diabetes. Or they may occur when blood sugar is high.
Being very thirsty
Feeling tired all the time
Having blurry eyesight
Feeling numbness or feeling tingling in your feet
Losing weight without trying
Urinating more often
For other people, these serious warning symptoms may be the first signs of type 1 diabetes, or they may happen when blood sugar is very high (diabetic ketoacidosis):
Deep, rapid breathing
Dry skin and mouth
Fruity breath odor
Nausea or vomiting; inability to keep down fluids
Low Blood Sugar
Low blood sugar (hypoglycemia) can develop quickly in people with diabetes who are taking insulin. Symptoms usually appear when a person's blood sugar level falls below 70 mg/dL. Watch for:
Rapid heartbeat (palpitations)
Exams and Tests
Diabetes is diagnosed with the following blood tests.
Random (non-fasting) blood glucose level. You may have diabetes if it is higher than 200 mg/dL, and you have symptoms such as increased thirst, urination, and fatigue. (This must be confirmed with a fasting test.)
Oral glucose tolerance test. Diabetes is diagnosed if the glucose level is higher than 200 mg/dL 2 hours after drinking a special sugar drink.
Visit your eye doctor at least once a year, or more often if you have signs of diabetic eye disease.
See the dentist every 6 months for a thorough dental cleaning and exam. Make sure your dentist and hygienist know that you have diabetes.
Because type 1 diabetes can start quickly and the symptoms can be severe. People who have just been diagnosed may need to stay in the hospital.
If you have just been diagnosed with type 1 diabetes, you may need to have a checkup each week until you have good control over your blood sugar. Your doctor will review the results of your home blood sugar monitoring and urine testing. Your doctor will also look at your diary of meals, snacks, and insulin injections. It may take a few weeks to match the insulin doses to your meal and activity schedules.
As your diabetes becomes more stable, you will have fewer follow-up visits. Visiting your doctor is very important so you can monitor any long-term problems from diabetes.
You are the most important person in managing your diabetes. You should know the basic steps of diabetes management, including:
How to recognize and treat low blood sugar (hypoglycemia)
How to recognize and treat high blood sugar (hyperglycemia)
Where to buy diabetes supplies and how to store them
Insulin lowers blood sugar by allowing it to leave the bloodstream and enter cells. Everyone with type 1 diabetes must take insulin every day.
Insulin must be injected under the skin using a syringe, insulin pen, or insulin pump. It cannot be taken by mouth because the acid in the stomach destroys insulin.
Insulin types differ in how fast they start to work and how long they last. Your doctor will choose the best type of insulin for you and will tell you at what time of day to use it. Some types of insulin may be mixed together in an injection to get the best blood glucose control. Other types of insulin should never be mixed. You may need insulin shots from 1 to 4 times a day.
Your doctor or diabetes nurse educator will teach you how to give insulin injections. At first, a child's injections may be given by a parent or another adult. By age 14, most children can give themselves their own injections.
People with diabetes need to know how to adjust the amount of insulin they are taking:
When they exercise
When they are sick
When they will be eating more or less food and calories
When they are traveling
Diet and Exercise
By testing their blood sugar levels, people with type 1 diabetes learn which foods and activities raise or lower their sugar levels the most. This helps them adjust their insulin doses to specific meals or activities to prevent blood sugar from becoming too high or too low.
The American Diabetes Association and the American Dietetic Association have information for planning healthy, balanced meals. It can also help to talk to a registered dietitian or nutrition counselor.
Regular exercise helps control the amount of sugar in the blood. It also helps burn extra calories and fat to reach and maintain a healthy weight.
Talk to your doctor before starting any exercise program. People with type 1 diabetes must take special steps before, during, and after physical activity or exercise.
Managing Your Blood Sugar
Checking your blood sugar levels yourself, and writing down the results, tells you how well you are managing your diabetes. Talk to your doctor and diabetes educator about how often to check.
To check your blood sugar level, you use a device called a glucose meter. Usually, you prick your finger with a small needle called a lancet to get a tiny drop of blood. You place the blood on a test strip and put the strip into the meter. The meter gives you a reading that tells you the level of your blood sugar.
Keep a record of your blood sugar for yourself and your health care team. These numbers will help if you have problems managing your diabetes. You and your doctor should set a target goal for your blood sugar level at different times during the day. You should also plan what to do when your blood sugar is too low or high.
Low blood sugar is called hypoglycemia. Blood sugar levels below 70 mg/dL are too low and can harm you.
People with diabetes are more likely than those without diabetes to have foot problems. Diabetes damages the nerves. This can make you less able to feel pressure on the foot. You may not notice a foot injury until you get a severe infection.
Diabetes can also damage blood vessels. Small sores or breaks in the skin may become deeper skin sores (ulcers). The affected limb may need to be amputated if these skin ulcers do not heal or become larger, deeper, or infected.
Because of nerve damage, you could have problems digesting the food you eat. You could feel weakness or have trouble going to the bathroom. Nerve damage can also make it harder for men to have an erection.
Blood sugar levels that are higher than the goals you and your doctor have set
Numbness, tingling, or pain in your feet or legs
Problems with your eyesight
Sores or infections on your feet
Symptoms that your blood sugar is getting too low (feeling weak or tired, trembling, sweating, feeling irritable, having trouble thinking clearly, fast heartbeat, double or blurry vision, feeling uneasy)
Symptoms that your blood sugar is too high (being very thirsty, having blurry vision, having dry skin, feeling weak or tired, needing to urinate a lot)
You are having blood sugar readings below 70 mg/dL
You can treat early signs of hypoglycemia at home by eating sugar or candy, or by taking glucose tablets. If signs of hypoglycemia continue or your blood glucose level stays below 60 mg/dL, go to the emergency room.
Type 1 diabetes cannot be prevented. There is no screening test for type 1 diabetes in people who have no symptoms.
Alemzadeh R, Ali O. Diabetes mellitus. In: Kliegman RM, ed. Kliegman:Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 583.
American Diabetes Association. Standards of medical care in diabetes -- 2014. Diabetes Care. 2014;37 Suppl 1:S14-S80.
Eisenbarth GS, Buse JB. Type 1 diabetes mellitus. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 32.
Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team. Editorial update: 05/14/14