Misdiagnosing Type 1 Diabetes

A recent Australian survey found that 33% of respondents with Type 1 diabetes were wrongly diagnosed with Type 2. Sixty-five percent of them had to go back to the doctor three or more times before they were correctly diagnosed. Why does this happen?


It happens because some doctors assume they know everything when in fact they have no clue. If a person walks in with high blood sugar, they “must” have diabetes. If they’re an adult who never had it before, it “must” be Type 2. End of story.

Actually, both of these conclusions are wrong. Causes of high blood sugar include pancreatitis, kidney or liver disease, infections, and steroid use, among others. And Type 1 can come on at any age. People can also have “Type 1.5,” meaning some other genetic or autoimmune problem that has characteristics of both Type 1 and Type 2 diabetes.

At Diabetes Self-Management, we get a lot of letters from people who have been told they’re Type 2, when they’re probably not. Mary wrote: “I am female, white, 47 [years old], 5′9″ 142 [pounds], a runner, and…recently [diagnosed] with type 2. No one else in my family has diabetes… I have never been obese… Go figure.”

Another commenter wrote: “My mother is 100 lbs soaking wet and has always been extremely active, walking sometimes several miles a day. She was diagnosed with Type 2 about 10 years ago. Her mother, also thin and very active, was also diagnosed with Type 2. Am I missing something?”

Maybe these women do have Type 2. It’s possible. As I wrote about here, there are thin, physically active Type 2s. But there are also millions of people who have late-onset Type 1, or LADA (latent autoimmune diabetes of adults) or MODY (maturity-onset diabetes of the young).

Because they’re not kids, doctors assume these newly diagnosed adults are Type 2. So they don’t give them insulin, even though they are not making enough of their own. Without adequate insulin, it is very hard to control blood glucose, unless you are exercising every waking hour of every day. So these people walk around with high blood glucose for years, making them likely to develop complications, which wouldn’t happen if they were treated correctly.

Emm from New Zealand wrote on Diabetes Forum, “I was 30ish when diagnosed and assumed to be T2. I struggled for around a year — first with strict diet changes, lots of regular exercise, then with pills but nothing was working. Finally an endocrinologist told me in a few seconds flat that I was a type 1. My father had the same story — but even worse. They wouldn’t allow him to start insulin for years. He was in a really bad way by the time they gave him insulin.”

Probably, his doctors blamed him for his high blood sugar levels, for not following their diet or exercising, when what he really needed was insulin. So here’s someone whose father had late-onset Type 1, and even then the doctors wouldn’t evaluate him for Type 1.

Now, you can’t assume someone doesn’t have Type 2, just because they’re thin. Rouhgly15–2 % of people who have Type 2 are thin, although if everyone were diagnosed correctly, that percentage might drop a bit. But it is estimated that 20% of Americans diagnosed with Type 2 may actually have LADA.

Please note that this is not just a concern for thin people. Melitta, who blogs frequently about misdiagnosis of Type 1, says “Many [heavy] people are lumped immediately into the T2 category but actually have Type 1. In my blog I have encouraged several overweight people to work with their doctors to get a correct diagnosis. They all… turned out type 1. In adults, it is easier to spot the misdiagnosed if they are thin, but adult-onset T1 happens to people of all weights.”

The important thing is to know whether your body is producing enough insulin. Doctors can test for this, and if you’re insulin-deficient, they should treat the problem.

The usual tests would be a c-peptide level and/or an insulin level. Each test might cost around $100 or more, so you may have to work with your doc to get them covered or to do it in the most cost-efficient way.

By the way, the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus says we should lose the term LADA, because it’s really just a form of slow-acting Type 1. They’re medical establishment, so I don’t trust them, but I’m looking into it. So this may be the last time you hear the term LADA from me.

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  • calgarydiabetic

    I think my case was a heavy diabetic that was eyeballed to be type 2 with 100% confidence by Calgary’s leading endo. No tests needed in his opinion. Well loosing 85 lb down to lower than high school football weight and 1 year of avandia at maximum dose did nothing for the blood sugar. Neither average nor standard deviation.

    I had to pound desks to be allowed insulin. I will always wonder had I been put on insulin promptly (and a low carb diet) if some of my pancreas would have remained alive making the disease fun instead of a horrible nightmare.

  • calgarydiabetic

    Ps another Endo said :” insulin you do not want to touch that s**t with a ten foot pole” Well now I need 100 units per day to survive poorly.

  • calgarydiabetic

    PS David this is an excellent article since the number of insulin dependent diabetics diagnosed as non insulin dependent is much higher than it should be. Patients must not take their doctor’s verdict as gospel when the evidence points in the opposite direction.

  • jim snell

    Aside from the type 1 and type 2 issues described here there is another aspect here.

    Using insulin does not necessarily make one a type 1. Being a type 2 does nort mean the oral stuff is really correct and useable.

    I am type 2 – insulin resistant.

    My pancreas eis still hauling butt.

    My body needs slight controlled boost of – liquid insulin – pills cannot do that. They are the uncontrolled applying a sledge hammer approach to a problem.

    In Europe, Doctots consider Insulin far earlier.

    After 30 years on that useless oral stuff, I am on 3 units of humalog lispro in morning and 2 units at lunch and dinner and I add it after my pancreas does its bolus and use it to hammer back peaks.

    Put me down fed up with the square box mentality of our industry and its approved solutions – not our good doctors struggling to keep this mess under control.

    I am not Insulin dependent as in the traditional Type 1 disease diagnosis and cure but
    Metformin is first key drug hauling butt and Insulin is a helpful boost even after 26 years doing wrong thing of just throw insulin at the problem.

    Type 1 and Type 2 diabetes are two totally different problems – one requires insulin doses to restore proper body operation while type 2 is a case of Insulin resistance brought about by glucose saturation and requires solving the Insulin Resistance issue and reasons and working disease from meds, diet and exercise to resolve. Insulin may be required as a boost for type 2 patients due to aging of pancrease and other damage but it is NOT the Key problem in my mind.

  • Tara

    I was diagnosed with type 2 at the age of 33 no history of diabetis in my family at 36 I was put on insulin I put on 2 stone in 10 days I decided to go private as I was getting nowhere with my dr
    I had a c peptides test which shows I am making my own insulin but my body is not using it so my problem was absorbsion I done some if my own research and have been using b vitamins and this has helped alot my specialist also put me in victozor an injection you take once a day this has helped to.

  • Nasiru Abubakar

    I was diognised with type 2 at the age of 34 no history family.So am now on medication.On other day,another doctor asked me to do another test call GLUTAMIC ACID DECARBOXYLASE(GAD) To see whether it is type 1 or 2.But up till now am not get where I can do it.What is way out ? Pls

  • David Spero RN

    Nasiru, I don’t know where you can get a GAD antibody test, partly because I don’t know where you are in the world. You can search on the Web. But there are other tests like the C-peptide level and insulin level that might be easier to get and tell you just as much.

  • John_C

    Don’t ya just love the way David flings these brave little articles out?? So brave! My doctor goes ballistic if I question his medical knowledge — even if he his wrong.

    When I was diagnosed as a Type 1 diabetic several years ago now, he suggested we try some treatment as a Type 2 and had limited success. So now I am a Type 2 with an A1c of over 12. To be brief life was a roller coaster and I hit the books (Internet).
    Using the Duck (if it walks and quacks like a duck) and Rose (a rose by any other name) theory I did discover I was neither. Turned out to me a form of LADA — the kind with changing insulin levels. But there were patterns that I finally figured out. I demanded insulin (which I got) but was left to figure out the treatment myself because I questioned my doctor’s wisdom.

    Short story: A1c today is 5.1 and I live my life a couple hours at a time, but so worth it. The many problems I had years ago have all but disappeared and I am a healthy senior (slim too).

    With all due respect to good medicine it was a rough road and I guess I sort of lost my friendship with my doctor (small community). But my life and good health is important TO ME. And YES I wish I had a real team to help me with this.

    Like other people this process was very long and it is so nice to have writers like David talk about it. Makes me feel a little better. Thanks!

  • Linda

    What we really, really need is a change in the diagnosis and treatment guidelines. I was diagnosed as Type 2 when I was IN DKA and made my own call — requesting C-pep and GAD-65 testing. Took me a YEAR to get insulin. Because, yes, I was fat and peri-meno, so I “looked like” T2D. Patients should not have to do their own research and diagnosis.

  • Susi

    Linda and I share a similar story, and Mellita knows my story too. I was first diagnosed with T2 at age 25, in 1978! I fought to get tested against “impossible” and similar comments. I had been misdiagnosed for 30+ years! In retrospect it all fits, but not a single doctor picked it up even when my A1C was 14! They much preferred to call me non-compliant. It’s really crazy that you almost have to be your own doctor to understand what needs to be tested and which diabetes you might have. Sadly, my daughter is now on a similar path, which I’ve caught very early. I’ve spoken to 2 doctors already and their responses were complete nonsense! Why don’t doctors get it yet?

  • sue

    i am thin 5’1, 105 pounds and was told i was type 2. i told the dr. i think you are wrong and did not take the oral meds and found myself a endo. he took blood work, and in 3 wks. i was told i have LADA (latent autoimmune diabetes adults) and started on a nighttime insulin called Lantus. its been one hell of a ride. the 1st 7 months all i did was cry (sadly 17 years ago i lost my sister Carol age 32) to diabetes and i was so frighten what lay ahead for me. i also am a registered nurse so i know what a difficult disease this ease. but… its been 1 year now and with the correct guidance of my health care team i am learning to adjust , eat right, exercise more and count carbs.. so please anyone with this disease type 1, 1.5, 2 whatever please take care of yourself. see your dr. every 3 months and learn and never stop learning and we all should live to a ripe old healthy age.. god bless you all and stay well. sue

  • sue

    forgot to mention my age 53 !.. i truly believe menopause was the button that pushed diabetes on.. did this happen to anyone else???

  • kelliejordan

    hi i am 26 an last year fell pregnant with my second baby. i got quiet sick an was diagnosed b4 i found out i was pregnant with diabetes. I had lost some weght an was generally unwell. Because of how my symptoms presented them selfs (my age an weight) i was assumed to be type 1 so through out my preg I was on insulin (novorapid an levemir). Half way through how ever my antibody results came bk an i was told i was t2. I came of insulin after i had my baby an i am currently on metphormin. I dont how ever feel great an im just wondering about this LADA i never heard of it. i have quite alot of cousins who were diagnosed as type 2 an go on to be type 1. My diet is ok but i do love choc i crave it i know it aint helping though (its hard). Eny advice on what i should do i knwo ill end up on insulin again eny how id say my body dosent really know how to cope now im off it. My docs thjink when i fell preg with my first baby i was gestational an it was never noticed as my baby was (10lb 8oz) a week early.