What Is Type 1 Diabetes? Symptoms, Causes, Diagnosis, and Treatment
Type 1 diabetes is an autoimmune disease that leads the body to stop making enough insulin to keep glucose (sugar) at a healthy, normal level. It is most often diagnosed in children and young adults, although it can develop at any age. (1)
In the normal digestive process, your body breaks down much of the food you eat into glucose, a simple sugar that’s stored in your body and used for energy. The hormone insulin, produced by the pancreas, regulates the amount of glucose in your blood by helping liver, muscle, and fat cells absorb the sugar. (2)
With type 1 diabetes, the body’s immune system attacks and destroys the pancreas’s insulin-producing beta cells. Without that hormone, blood sugar rises too high, causing hyperglycemia.
“We don’t know exactly what triggers this autoimmune process to start,” says Charles Scott Thomas, MD, an endocrinologist at Kaiser Permanente Los Angeles Medical Center in Los Angeles. “There is likely a genetic component that places patients at risk, with some environmental influences as well.”
People who have type 1 diabetes must replace insulin every day through injections or infusion and monitor their blood glucose throughout the day. (1)
Type 1 and type 2 diabetes produce the same result: blood sugar that is too high. But they do it in very different ways.
As mentioned, type 1 diabetes is an autoimmune disorder that results in the body being able to produce little or no insulin. It cannot be prevented. (3)
Type 2 diabetes develops when liver, muscle, and fat cells don’t respond properly to insulin and become “insulin resistant.” Glucose doesn’t enter the cells as efficiently as before and instead builds up in the bloodstream.
In type 2 diabetes, the pancreas responds to these increased blood glucose levels by producing more insulin. Eventually, however, it can no longer make enough insulin to handle spikes in glucose levels, such as routine rises in blood sugar after a meal.
Type 2 diabetes accounts for 90 to 95 percent of all diagnosed cases of diabetes. It can be prevented or delayed in many cases with diet and exercise changes. (4)
Symptoms of type 1 diabetes can develop rapidly, especially in young people, says Sanjoy Dutta, PhD, chief scientific officer for the type 1 diabetes research organization JDRF. Symptoms may include: (1)
Dr. Dutta says sometimes the weight loss is very precipitous. “In some cases, it might even be 10 kilos (22 pounds) of weight loss within two weeks.”
The onset of type 1 diabetes can be difficult to detect in very young children, says Dr. Thomas. “The signs of something wrong may be more subtle, such as more wet diapers or heavier diapers, bedwetting, and increased thirst.”
Another symptom of type 1 diabetes can be life-threatening, and particularly for young people who are less likely to understand what they are going through, says Dutta. Diabetic ketoacidosis (DKA) happens when insulin drops and the body can’t use your rising blood glucose as fuel; it turns to burning fat instead, leading to a too-rapid buildup of acids in the bloodstream, known as ketones. Symptoms of DKA can include: (5)
It’s important to seek immediate medical attention for DKA, and it may involve a hospital trip. A blood or urine test for ketones can detect DKA. Treatment involves insulin injections and fluid replacement. (5)
Frequently, a bout of DKA is what leads to a diagnosis of type 1 diabetes, particularly in young people. Dutta says this can happen to anyone with type 1 diabetes at any age, but if a person develops the disease in their middle or later years, the progression is typically more gradual, and they are therefore more likely to already be under a doctor’s care for high blood sugar.
It’s unknown exactly what causes type 1 diabetes, but experts think it could be a combination of genetic and environmental factors. (1) For instance, the risk of type 1 diabetes is increased if you have certain variants of genes in the human leukocyte antigen (HLA) complex. These genes are involved in making proteins that play a critical role in immune response. (6)
Coxsackieviruses have been studied as possible triggers for type 1 diabetes, and prolonged viral infection may increase a child’s risk for developing the disease. (7)
Other possible risk factors for type 1 diabetes include:
In fact, the odds that a man with type 1 diabetes has a child who develops it are 1 in 17. For a woman who bears a child before age 25, that risk is 1 in 25, but it drops to 1 in 100 if the child is born after she is 25. (9)
Yet 80 percent of people with type 1 diabetes have no family history of the disease. (10)
“Testing for the diagnosis of type 1 diabetes first involves testing for abnormally high blood sugar,” says Thomas. “The next steps are uncovering if the high blood sugar is due to the pancreas having lost the ability to make adequate insulin, and testing for higher-than-normal levels of the antibodies that are often identified in type 1 diabetes.”
Your healthcare provider may order the following tests to diagnose type 1 diabetes.
Random plasma glucose test, which checks if your blood sugar is too high and doesn’t require fasting before your blood sample is drawn. A reading higher than 200 milligrams per deciliter (mg/dL) with symptoms of high blood sugar indicates you have diabetes. (1,11)
Hemoglobin A1C test shows how high your blood sugar has been, on average, over the past three months. A blood sample is drawn, and it doesn’t require fasting beforehand. An A1C of 6.5 or higher indicates diabetes. (11)
Fasting plasma glucose test checks how high your blood sugar is after you’ve had nothing to eat or drink except small sips or water for at least eight hours. A reading higher than 126 mg/dL points to diabetes. (11)
Your doctor may order a diabetes autoantibody panel to detect autoantibodies that attack insulin or cells in the pancreas related to its production, as well as certain enzymes. (12)
The following may also be ordered to diagnose type 1 diabetes: (12)
Dutta recommends seeing an endocrinologist for treatment if you’re diagnosed with type 1 diabetes. “I’m not saying that a general practitioner will not be helpful, but a primary care physician doesn’t have the specialty knowledge to deal with type 1 diabetes, which is a very different disease from type 2 diabetes.”
The average person with a type 1 diabetes diagnosis who makes it to age 43 has a life expectancy that is nearly eight years shorter than someone the same age without that diagnosis, according to a study published in 2020. (13)
That is slightly less than the life expectancy reported in a 2015 Scottish study that found men with type 1 diabetes at age 20 had a life expectancy about 11 years shorter than men who didn’t have the disease. For women, the decrease in life expectancy was 13 years, the study found. (14)
How well you manage type 1 diabetes can affect your life expectancy.
In another study, also published in 2015, researchers found that people with type 1 diabetes who underwent intensive treatment for 6.5 years experienced a modestly reduced risk of complications and a lower overall risk of early death. (15)
Type 1 diabetes is a lifelong illness that requires careful, daily management of blood sugar levels. “The constant need to be thinking about diabetes can grow tiresome and frustrating for many young people,” says Thomas. “While their journey will be different from the experience of those who don’t have type 1 diabetes, they can still live a fulfilling, successful life, and they may find that their unique experience gives them the ability to tap into an inner power they didn’t realize they had.”
Dutta strikes a similarly optimistic tone. “Do we have a cure? No. We have advances in the clinic, but not yet an approved therapy that cures type 1 diabetes.” But, he adds, continuing advances in glucose monitoring and insulin delivery are making it easier for people to manage life with the disease.
“The cornerstone of type 1 diabetes management continues to be insulin therapy,” says Thomas. Combined with glucose monitoring, this is the primary way that blood sugar is kept within a healthy range every day.
Two main types of insulin are injected to get you through the day: (16, 17)
Insulin therapy typically involves injecting yourself up to several times daily using one of the following methods: (18)
A slim majority of the 7.4 million insulin users in the United States (53 percent) were injecting with vials and syringes as of 2016, followed by prefilled insulin pen users (46 percent). (19) An estimated 350,000 people use pumps in the United States. (20)
An essential part of managing type 1 diabetes is glucose monitoring. People with the disease typically monitor their own blood sugar, using one of the following methods:
“Patients are able to get real-time information about their blood sugar and also see trends,” says Thomas. That serves to help them to understand how food, sleep, exercise, and stress all affect their blood sugar, and how to avoid risky swings in glucose levels.
“When an insulin pump and CGM are integrated, the CGM can deliver information to the pump about the patient’s current blood sugar level and the trend of the blood sugar. This allows the pump to potentially alter insulin delivery to help maintain blood sugars more within a healthy range,” says Thomas. “While the patient still needs to be very involved with his or her own diabetes management, these devices offer a helping hand.”
Less-common type 1 diabetes treatments include:
Doctors aren’t aware of a way to prevent type 1 diabetes, but researchers have made progress and are continuing to explore ways to do so or at least slow its progression. (1)
For instance, the monoclonal antibody drug teplizumab was approved by the FDA in November 2022. Studies found it delayed the onset of type 1 diabetes by an average of two years in people who had relatives with the disease. (26,27)
Having prolonged high blood sugar can lead to a host of health problems. They include: (28)
Having any type of diabetes can also put you at greater risk for complications from COVID-19, the respiratory disease caused by the novel coronavirus. “We know that patients with uncontrolled diabetes and COVID-19 infection experience more severe symptoms of COVID-19, can have more extensive lung involvement, and die more often,” says Thomas. Nearly 40 percent of COVID-19 deaths in the United States during the first few months of the pandemic happened to people who had diabetes. (29)
There is no one-size-fits-all diet or exercise plan for people with type 1 diabetes. But a healthy lifestyle will help you keep your blood sugar in a healthy range. Be sure to speak with your doctor before embarking on any diet or exercise plan, to ensure you are making changes that are safe and appropriate for you. (30)
A registered dietitian nutritionist (RDN), and especially one who is also a certified diabetes care and education specialist (CDCES), can help you to find the meal plan that is right for you. Ask your healthcare provider for a referral or search the Academy of Nutrition and Dietetics directory for an RDN in your area. (31)
Whatever diet you settle on is likely to include some form of carb counting (monitoring your intake of carbohydrates, which break down into glucose); and a balance of protein, fat, and fiber to help stabilize blood sugar. (30)
Your healthcare team can help you decide the right balance, taking into account any medication or insulin you’re on. But the recommended amount of carbs for most people with diabetes in general is 45 to 65 percent of total daily calories. (32)
Keeping all that in mind, any healthy diet is likely to draw from the following, per federal guidelines: vegetables; fruits; whole grains; fat-free or low-fat milk and milk products (unless you are vegetarian); lean meats; poultry; fish; beans; eggs; and nuts and seeds. Keep your intake of saturated fats, cholesterol, salt, and added sugars to a minimum. Avoid trans fats. (33)
Physical activity is another important aspect of diabetes management. Just make sure to check in with your healthcare provider before embarking on an exercise plan. Complications of diabetes, such as nerve damage or the risk of low blood sugar, may require adjustments in how you exercise. (34)
Taking that into account, aim for at least 150 minutes to 300 minutes a week of moderate-intensity exercise or 75 minutes to 150 minutes a week of vigorous-intensity aerobic physical activity. It’s moderate-intensity if you can talk, but not sing, during the activity; and vigorous-intensity activity if you can’t say more than a few words without pausing to take a breath. Again, your healthcare provider will help determine the right course of exercise. (35)
Type 1 affects people of all ages. Here are some more facts and figures on type 1 diabetes:
Although type 1 diabetes is most prevalent in the United States among white people, Hispanic (4.4 percent), non-Hispanic Asian and Pacific Islander (4.0 percent), and Black (2.7 percent) children and youths saw the steepest annual percentage increases in cases between 2002 and 2015. (38)
Youths of the Black, Indigenous, and People of Color (BIPOC) communities, particularly those who are socioeconomically disadvantaged, are more likely to have DKA at diagnosis, says Thomas. The authors of a 2018 study (in which Thomas was not involved) surmised that insurance access and parent education accounted for much of the difference. (39)
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