Once known as “juvenile” diabetes, type 1 diabetes was long considered a childhood disease. Although the condition is often diagnosed in children and teenagers, it can develop at any age.
Type 1 diabetes occurs when the immune system attacks and destroys cells in the pancreas that produce insulin, resulting in dangerously high blood-glucose levels. Treatment requires daily insulin therapy.
Type 1 diabetes tends to develop rapidly in children, often creating a risk of diabetic ketoacidosis (DKA). At later ages, however, the condition often develops more slowly and can sometimes be misdiagnosed as type 2 diabetes.
What Is Diabetic Ketoacidosis (DKA)?
Diabetic ketoacidosis (DKA) is a serious and potentially life-threatening complication of diabetes.
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Type 1 Diabetes Development in Childhood and Adolescence
The most common ages of diagnosis for type 1 diabetes are between 4 and 6 years old and 10 to 14 years old. Diagnoses peak at age 10 for boys and age 12 for girls.
This is why type 1 diabetes is often associated with children. Only about 5 to 10 percent of people with diabetes have type 1 diabetes, far fewer than the number with type 2 diabetes, which is a slower-progressing condition in which the body develops a resistance to insulin and does not process it normally.
In childhood, the full onset of type 1 diabetes comes on quickly, says Egils Bogdanovics, MD, a diabetes and metabolism endocrinologist at Charlotte Hungerford Hospital in Torrington, Connecticut. Insulin production declines rapidly while blood glucose levels increase rapidly. This leads to the sudden development of type 1 diabetes symptoms, which include:
Unexplained weight loss
Change in vision
Extreme thirst
Increased need to urinate
Intense fatigue
Hunger after eating
Sour-fruit odor on the breath
About 30 percent of children who develop type 1 diabetes are diagnosed when they’ve already developed DKA, a condition defined by toxic levels of ketones in the blood that result from dangerously low levels of insulin. DKA is a potentially deadly health emergency.
About 18,000 people ages 20 and younger receive a type 1 diabetes diagnosis each year, with that number increasing since 2002. Type 1 diabetes comprises at least 86 percent of all diabetes diagnoses for that age group.
Infants also can develop type 1 diabetes, though it is less common, Dr. Bogdanovics says.
Neonatal diabetes also may be diagnosed in babies less than a year old, usually in the first six months of life. These cases are rare, and about 80 percent are attributed to a genetic mutation, rather than an autoimmune disorder.
Type 1 Diabetes Development in Adulthood
Although type 1 diabetes often is diagnosed in childhood, it also can develop through adulthood. In fact, research shows that 62 percent of type 1 diabetes diagnoses come in people ages 20 and older. Bogdanovics says he has diagnosed it in adults in their 80s.
In adults, type 1 diabetes can develop slowly because the immune system’s attack on the pancreatic cells that produce insulin is also slower. It might require further testing and resemble type 2 diabetes for months or years.
People who develop an especially slow-developing form of insulin-reliant diabetes called latent autoimmune diabetes in adults (LADA), sometimes called type 1.5 diabetes, may wait years before receiving a proper diagnosis.
“Unfortunately, it’s easy for these people to be misdiagnosed with type 2 because of how slowly LADA develops,” Bogdanovics says. “This refers directly to how much slower the attack on the pancreatic cells is compared to the rate of attack in children.”
Michael Fang, PhD, an assistant professor at Johns Hopkins University’s Bloomberg School of Public Health, says he believes that many doctors are unaware of how frequently type 1 diabetes develops in adulthood, potentially leading to misdiagnosis and suboptimal treatment.
“I think one big contributor is the misconception that type 1 diabetes is a childhood disease,” Dr. Fang says. “As a result of this, providers may assume that all adult patients have type 2 diabetes, even if they do not fit the ‘classic’ clinical picture of a type 2 diabetes patient.”
It is possible that as many as 40 percent of adults who are at least 30 years old with a type 1 diabetes diagnosis have been misdiagnosed with type 2 diabetes.
Bogdanovics says that an adult with suspected type 2 diabetes may not receive insulin treatment immediately, though it will eventually become necessary for managing type 1 diabetes. Type 1 diabetes is typically a more challenging condition, and the life expectancy for people with type 1 diabetes is about five years fewer than that of people with type 2.
“Guidelines currently recommend that providers test for autoantibodies when they suspect an adult patient ‘may’ have type 1 diabetes,” Fang says. “I suspect this isn’t performed very often, partly because of the lack of awareness that type 1 diabetes can occur in adults.”
If you cannot control your blood sugar and think you’ve been misdiagnosed with type 2 diabetes, you can get further testing to clarify your diagnosis. Talk to your endocrinologist or primary care doctor, who may recommend tests that include:
C-peptide test: This measures the amount of insulin your body is producing. In type 1 diabetes, C-peptide is low; it is traditionally high in type 2 diabetes.
Autoantibody test: Autoantibodies, or malfunctioning proteins, indicate that the immune system is attacking and destroying the cells in your pancreas that produce insulin.
Screening for Early Diabetes
Though most people with diabetes are only diagnosed after they have already experienced very high blood sugar levels, it is possible to identify type 1 diabetes before significant symptoms develop.
Screening for type 1 diabetes requires a blood test for autoantibodies. It can allow doctors to pinpoint early stages of type 1 diabetes before the condition becomes dangerous.
“What this really means is that type 1 diabetes starts potentially years before you actually know you have diabetes, unless you get antibody testing,” Bogdanovics says.
Screening is usually recommended for people with a family history of the condition, especially for children of parents with type 1 diabetes.
Nearly 90 percent of people who develop type 1 diabetes, however, have no family history of the condition. This has led some experts to recommend that all children be screened for the autoantibodies that cause type 1 diabetes, regardless of symptoms.
Identifying type 1 diabetes at an early stage can help reduce the risk of DKA. The U.S. Food and Drug Administration has approved the drug teplizumab (Tzield) for people ages 8 and older with certain stages of diabetes. It can delay the full onset of type 1 diabetes by protecting the pancreas’s ability to produce insulin. Ask your doctor if it is appropriate for your situation.
The Takeaway
Although type 1 diabetes is often diagnosed in children, it can develop at any age.
Type 1 diabetes tends to progress very quickly in children, with symptoms including intense fatigue, extreme thirst, and unexplained weight loss.
In adults, type 1 diabetes may have a slower onset and may initially be misdiagnosed as type 2 diabetes.
If you are unsure what type of diabetes you have, or if your diabetes treatment isn’t working, it may be wise to ask your healthcare provider to confirm your diagnosis.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Gregory GAH et al. Global Incidence, Prevalence, and Mortality of Type 1 Diabetes in 2021 With Projection to 2040: A Modelling Study. The Lancet Diabetes & Endocrinology. October 2022.
Anna L. Goldman, MD, is a board-certified endocrinologist. She teaches first year medical students at Harvard Medical School and practices general endocrinology in Boston.
Dr. Goldman attended college at Wesleyan University and then completed her residency at Icahn School of Medicine at Mount Sinai Hospital in New York City, where she was also a chief resident. She moved to Boston to do her fellowship in endocrinology at Brigham and Women's Hospital. She joined the faculty after graduation and served as the associate program director for the fellowship program for a number of years.
Ginger is a freelance writer and editor with a bachelor's degree in professional writing, and a background in cognitive coaching, video blogging, record-setting competitive powerlifting, personal training, Ashtanga yoga, and motivational speaking.
She lives in Vermont with a handsome husband, two daughters, and a loyal dog named Pedro.
