Adults Can Get Type 1 Diabetes, Too
David Lazarus had just moved to Los Angeles to start a new job as a business and consumer columnist for the Los Angeles Times when he suddenly developed some of the classic signs of diabetes: extreme thirst, fatigue and weight loss. He dropped close to 15 pounds in two weeks.
Lazarus was in his early 40s. "The weight loss was the first big red flag. It happened really fast," he says. He consulted a physician, who diagnosed him with Type 2 diabetes and recommended a "monastic" low-carb, macrobiotic diet.
When he continued to feel lousy a few days later, Lazarus spoke with another physician. That doctor suggested that Lazarus might have Type 1 diabetes, an autoimmune condition in which the insulin-making cells in the pancreas are attacked and destroyed. But that physician didn't take insurance.
Finally Lazarus made his way to the diabetes center at the University of California, Los Angeles. There, an endocrinologist diagnosed him with Type 1 diabetes and immediately put him on the correct treatment, insulin.
Without insulin injections or infusion via a pump, people with Type 1 diabetes typically fall into a coma and die within days to weeks, although sometimes adults may have a small amount of reserve insulin that keeps them going longer. Still, eventually all people with Type 1 diabetes must receive insulin.
Lazarus' story is not uncommon. It has long been thought that Type 1 diabetes arises primarily in childhood or adolescence and only rarely in adulthood. In fact, Type 1 diabetes was formerly called "juvenile" diabetes, and that term is still widely used, even though the terminology was officially changed in 1997.
Across the ages
Now, it looks as if not only can Type 1 diabetes occur in adults, it's just as likely to appear in adulthood as in childhood or adolescence.
Using data from a resourcecalled the UK Biobank, Dr. Nicholas J. Thomas and colleagues from Exeter University applied a genetic risk score that they developed from 29 genes commonly associated with Type 1 diabetes to 13,250 people who developed diabetes over the first 60 years of their lives.
Overall, 42 percent of cases of Type 1 diabetes started when people were 31 to 60 years old, while 58 percent were diagnosed at age 30 or younger. Type 1 was equally likely to appear across the first six decades of life, whereas the occurrence of Type 2 diabetes rose dramatically with age, accounting for 96 percent of cases in the 31-60 age group.
Type 2 diabetes is generally associated with obesity and is initially treated with diet, exercise, and medications other than insulin (although some do end up taking insulin eventually).
Compared to the Type 2 group, those with Type 1 of all ages were generally thinner, were more likely to have begun insulin treatment within a year of diagnosis, and were more likely to have experienced ketoacidosis, a dangerous metabolic condition that arises when the body lacks insulin.
The results were published Nov. 30 in Lancet Diabetes & Endocrinology.
Easily overlooked, not easily detected
The huge preponderance of Type 2 diabetes among adults at least partially explains why Type 1 historically has been believed to occur primarily in youth: When a child develops diabetes, it gets noticed. Among adults, there are so many with Type 2 that those with Type 1 are easily missed. Even if they end up on insulin treatment fairly quickly, they may still be assumed to have Type 2. (Further complicating matters, some overweight and obese children are now developing Type 2 diabetes.)
Problematically, there is no single definitive test that doctors can use to distinguish the types. A protein called C-peptide indicates whether the pancreatic islet cells are making insulin, but some people with Type 1 will still have low levels of C-peptide in the first few years after diagnosis.
There are tests to measure the antibodies attacking the islet cells, but people with Type 2 may also have those antibodies. "It is common for an adult who develops Type 1 diabetes to be initially diagnosed as Type 2, particularly if overweight and there is no family history of Type 1 diabetes," says Dr. Roy W. Beck, executive director of the Jaeb Center for Health Research in Tampa.
"In a thin adult who develops diabetes, Type 1 should be strongly considered but in an overweight adult who develops diabetes, Type 1 is still possible," he says. But eventually, the U.K. researchers hope to develop their genetic test for general use along with other measures to enable doctors to more easily pick out the adults with Type 1 diabetes.
"I thought I'd dodged the bullet"
In hindsight, Lazarus' diagnosis should have been easy, since he's not overweight and he does have a family history of Type 1 diabetes. His father, brother and aunt all had it, but they'd been diagnosed at much younger ages – his aunt was a child (and subsequently died of the condition in young adulthood) and his father and brother were in their early 20s.
"I thought I'd dodged the bullet,' Lazarus says. "I've always been very healthy, and very careful about what I eat. By making it into my 40s, I thought cool, I'm the one who managed to skirt it. But then it came on with a vengeance."
Today, he's doing fine. He wears an insulin pump and a continuous glucose monitor, and works hard to keep his blood sugar levels normal.
But his story could have been different had he not been so persistent — he is a consumer reporter, after all — in seeking appropriate care. He advises others diagnosed with diabetes to do the same. "Your treatment regimen should be producing good [blood sugar] numbers. If you're not getting the data you want to see, then something's wrong."
Miriam E. Tucker is a freelance journalist specializing in medicine and health. You can follow her on Twitter: @MiriamETucker
Copyright 2021 NPR. To see more, visit https://www.npr.org.