Misdiagnosed: Why So Many Adults Start Type 1 Diabetes With the Wrong Map
When adults are diagnosed with type 1 diabetes, the story too often starts in the wrong chapter.
They walk into a doctor’s office tired, thirsty, and scared, and walk out with a metformin prescription and a “Welcome to type 2” packet. Months—sometimes years—later, they discover they never had type 2 at all. They had type 1 the whole time.
I’ve heard this story more times than I can count on the Juicebox Podcast. Smart, responsible people, doing everything right, following the plan—and still running numbers so high you could fry an egg on them. They’re told they’re “non-compliant,” when in reality, they were never given the right tools for the job.
The Quiet Epidemic No One Talks About
Here’s what the research says: nearly than half of all new type 1 diagnoses actually happen in adults.¹ In some studies, as many as 4 in 10 adults with type 1 are first told they have type 2.²
That means thousands of people spend months chasing an answer that insulin could’ve solved on day one. Blood sugars climb, energy disappears, and people blame themselves for “failing” a treatment plan that was never meant for them.
Jenny Smith, CDE—my partner in the Bold Beginnings series—put it perfectly: adults with new-onset type 1 don’t get the same structured education kids do. There’s no hospital crash-course in carb ratios and correction factors. Most adults get a pamphlet and a pat on the back.
So they start managing diabetes with the wrong diagnosis, the wrong meds, and zero guidance. It’s like being handed a map of Spain when you’re trying to drive through Nebraska.
Why It Keeps Happening
Age Bias If you’re over 25, many doctors assume type 2 by default. They look at your birth date, not your antibodies.
Testing Gaps Most adults never get the GAD or C-peptide tests that prove autoimmunity. Without them, the diagnosis is guesswork.
Treatment Inertia Providers “start with metformin” even when insulin is clearly needed. Every extra month on the wrong med is another month of damage.
Language Barrier People hear words like basal, bolus, glycemic load, and think they’ve fallen into medical Scrabble.
And then there’s the human side. Imagine watching your blood sugar skyrocket after eating an apple, calling your doctor, and hearing, “You just need more exercise.” It’s maddening. By the time someone finally runs the right tests, the patient is exhausted, frustrated, and convinced they’re bad at this.
What Misdiagnosis Costs
It’s not just numbers on a meter—it’s trust.
Physically, prolonged high glucose levels can fast-track complications. Emotionally, it’s like fighting a battle blindfolded. Many people describe a period of guilt, of feeling “broken.” They weren’t. They were just holding the wrong instructions.
Even after the correct diagnosis, there’s fallout. People become wary of their doctors. They hesitate to ask questions. They second-guess every bit of advice. Rebuilding confidence takes time—and that’s where education comes in.
Fixing the System (and Yourself)
You can’t change how the healthcare system works overnight, but you can arm yourself with the right expectations.
1. Ask for Antibody Testing Immediately
If you’re newly diagnosed and things aren’t adding up, request these tests:
GAD65, IA-2, and ZnT8 antibody panels
C-peptide to measure natural insulin production
If your provider balks, remind them the ADA encourages clinicians to consider islet-autoantibody testing — especially in adults whose presentation doesn’t fit the usual type 2 pattern..
2. Question Age-Based Assumptions
Type 1 doesn’t “age out.” The immune system can flip at 8, 38, or 68. If your treatment isn’t working, it might not be you—it might be your diagnosis.
3. Get the Education You Deserve
Kids with new-onset diabetes get hours of training, dietitians, and nurses who walk them through every beep of a pump. Adults get a handshake.
That gap is why we built Bold Beginnings—to give grown-ups the same foundation kids get, just without the hospital gown.
4. Find Your Language
Understanding terms like basal, bolus, correction factor, and time in range isn’t about memorizing jargon—it’s about speaking the language of your own care. Once you can name what’s happening, you can manage it. (And if those words still sound foreign, you’ll love our next piece: Foundations—Learning the Language of Diabetes.)
5. Don’t Be Afraid to Start Over
Getting re-diagnosed as type 1 can feel like failure. It’s not. It’s the moment the fog lifts.
The day insulin enters the story is usually the day the story starts making sense.
What It Really Means
Every week, more adults are diagnosed with autoimmune diabetes. Some will get the right answer quickly; many won’t.
But here’s the truth: you can’t manage what you don’t understand—and you can’t understand what you’ve never been taught.
That’s what Bold Beginnings is for. It’s the foundation class everyone should get on day one. It’s where Jenny and I break down the big words, the scary numbers, and the guilt that sneaks in between them.
If you’re newly diagnosed—or newly correctly diagnosed—start there.
Because once you have the right map, the road ahead may still twist and turn, but at least you’ll know where you’re going.
References
Thomas NJ et al. The Diabetologia Study on Adult-Onset Type 1 Diabetes Misclassification. 2020.
Davis AK et al. Clinical Features and Diagnosis of Latent Autoimmune Diabetes in Adults (LADA). Diabetes Care, 2019.
American Diabetes Association. Standards of Care in Diabetes – 2025.
