Misdiagnosis common among adult diabetes patients, study finds

TUESDAY, Oct. 9, 2018 (HealthDay News) – It’s not always easy – even for doctors – to tell if someone has type 1 or type 2 diabetes when they’re diagnosed as an adult.

And a new study finds mistakes are common.

That’s what happened to British Prime Minister Theresa May when she was diagnosed with type 2 diabetes in 2012. She was in her 50s at the time. Despite having all of the symptoms common to type 1 diabetes, including rapid weight loss, her doctor initially said she had type 2 diabetes.

After the prescribed medications didn’t help, May’s doctor ran more tests and realized she had type 1 diabetes. Her daily regimen was quickly changed from oral medications to injections of the hormone insulin.

“My very first reaction was that it’s impossible because at my age you don’t get it,” May told Diabetes U.K. “But then my reaction was: ‘Oh no, I’m going to have to inject’ and thinking about what that would mean in practical terms.”

So, how do doctors mix up the two conditions?

It’s really hard to tell the difference in adults, study author Dr. Nick Thomas said.

“In childhood, almost all diabetes is as a result of type 1 diabetes. After 30 years of age [there’s] a dramatic increase in type 2 diabetes, and type 1 represents less than 5 percent of all cases of diabetes, so trying to identify cases is like finding a needle in a haystack,” Thomas said. He’s a clinical academic fellow at the University of Exeter in England.

There’s also a common misconception that type 1 diabetes can only occur in children. But that’s not the case.


By Serena Gordon
HealthDay Reporter


I think also some doctors aren’t necessarily thinking of Type 1 as a possibility with people. A lot of people don’t realize the differences between Type 1 and Type 2 Diabetes.

I was diagnosed in the 90’s as a teenager and the doctor I went to see assumed I had Type 2 after blood tests showed a 485 blood sugar. I had lost 20 pounds and was complaining of no energy. The doctor put me on pills to and luckily I talked to someone who knew more about it the next week and told me there was no way I had Type 2. You would think now a days it would be easier to diagnose but it doesn’t seem that way.

Also, I have seen an Endocrinologist who had tons of patients and didn’t realize how certain long acting insulins don’t work as long in a Type 1’s body. He had my blood sugar fluctuate from over 400 to 20 or 30 on a daily basis. So I was going without insulin coverage for several hours a day. Very scary.

Hopefully people will become more aware of these differences.

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The article is a bit confusing to me. Wouldn’t a simple anti-body test confirm the type?


Wouldn’t a simple anti-body test confirm the type?

Not always! My first antibody test was negative, my second (a year later) was positive. And some Type 1s never test positive for antibodies (“Idiopathic Type 1” or Type 1b). Personally, I suspect there are more “types” of Type 1 than we currently have tests to confirm. For example, there exists some significant number (5-10%?) of Type 1s who test positive for the Zinc Transporter 8 antibody (ZnT8 test), but who would have not tested positive if they’d been tested for Type 1 antibodies before the test was developed, since some Type 1s test positive only for ZnT8.

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When I was diagnosed in 1986, at the age of 21 (first as flu, though I had every classic symptom of undiagnosed type 1 diabetes) they didn’t know what caused it. They still did all kinds of tests when my BG was discovered to be 998 (thank god my family ignored my doctor’s diagnosis and brought me to the ER 6 hours after my doctor’s appointment). I was told that my body didn’t seem to be making insulin (duh!), but I was also put on type 2 medications for a few months (until they found that they didn’t make any difference). I don’t think that I have ever been tested for antibodies.

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@Ruth4 - I continually find it amazing that testing for the typical panel of Diabetes related antibodies is not a basic first step in diagnosis.

I suspect this has a great deal to do with the particular doctor involved.

I was just speaking with somebody who informed me that they had recently progressed from Type 2 to Type 1 as their pancreas no longer produces insulin. This person stated this was specifically what their primary Endo healthcare provider had told them. When I tried to say this was not possible and perhaps they were simply misdiagnosed initially, the conversation immediately moved to the education credentials of the healthcare provider as compared to me. I backed away from that discussion pretty darn quick.

Our Endo healthcare provider (the entire system) certainly uses the typical Diabetes panel of antibody tests as a standard diagnostic tool. Additionally, they run the Celiac and Thyroid panel of antibody tests for all people newly diagnosed with T1D as a standard practice.

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This is really unfortunate. However, I wonder if there are still some old style doctors that believe us patients can’t or don’t want to be bothered with all those medical details. Saying progressed from type 2 to type 1 is short and sweet. (But maybe confusing since if progression, wouldn’t it be type 1 to type 2?).

It is time consuming to explain the details, and admit they may have missed diagnosing early Type 1 to begin with. :wink:

Or they may actually believe what they are saying, much worse.

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I think what they are really saying is that the condition has deteriorated to the point that the pancreas no longer make any insulin… hence, T2 to T1, being the state of having to supplement insulin. That was the belief before the all-knowing medical profession found out that T1 was caused by an autoimmune attack and T2 was due to Insulin Resistance. These are old time doctors who should have stopped working a long time ago. Ignorance abounds!

If the deterioration is to the point of requiring insulin, but auto immune testing is negative, I believe it it still considered type 2.
But many are told they are insulin dependent, causing confusion if they are Type 1 or type 2.
At one time the term insulin-dependent was the factor for differentiation between types, replacing the term juvenile diabetes. So it’s always a confusing topic.


So how does one tell type 1 from type 2 then?
or 1b from type 2?

They say there are type 1’s with negative antibodies but I have seen no other tests to prove type 1.

Also if someone who is type 2 has a pancreas that shuts off like a type 1 what caused it? (assuming no antibodies and good A1C levels) The only reason I’ve seen for a type 2 to progress would be with bad control and high glucose levels damaging the pancreas.

Seems like there is still a lot unexplained.

In early type 2, it should be relatively easy to distinguish if the correct tests are done.

T2 should present with high insulin, insulin resistance, and high blood sugars. The key pathology comes with insulin resistance.

T1 should present without insulin resistance (though this is not always true as one can have t1 and insulin resistance), but with low levels of insulin. This can be tested directly and/or with c-peptide testing (and blood sugar testing because c-peptide has to be interpreted with reference to blood sugar levels at the time of testing), and high blood sugars.

T1 may be rapid or slow onset. It may also be present with or without detectable antibodies. This is where the picture may not be so clear if the attending physician doesn’t want to look critically at the patient.

Presence of other autoimmune conditions should also raise the bar for suspicion of t1 vs. t2. Lack of family history of T2, should also raise suspicion for t1, though of course family history of T2 doesn’t mean patient can’t have t1.

Failure to respond to t2 medications and/or dietary / lifestyle interventions fairly rapidly should also raise suspicion for t1. In my Lada group I see so many stories of people misdiagnosed for years, and with horrific complications, and the drs blaming the patient for not being adequately compliant with treatment… :frowning: So this t1 - t2 is a bit of a crusade for me…


My fasting glucose was in the 300 to 400 range at diagnosis.
I was tested about yearly and was labeled “pre-diabetic” till my diagnosis as a “type 2”.

At diagnosis I never had insulin measurements but did have C-Peptide fasting tests right in the middle of the normal range. A1C was over 13%. I began Metformin and Victoza.

I very soon needed insulin in the next year, after Victoza stopped helping enough. I was then tested for antibodies and found none. After that regular C-Peptide tests were done mostly to help me eventually qualify for Medicare coverage.

I never got what I would call good control till I had a CGMS and a pump. My A1C came right down to 5.5% area and has stayed there.

I never found diet or exercise any help as to diabetes treatment but has helped my health generally.

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I don’t think it is actually that difficult to correctly diagnose an adult with new-onset Type 1 diabetes–I think doctors are making excuses for misdiagnoses. But multiple problems can cause misdiagnosis: 1) doctors still cling to the myth that Type 1 is a childhood disease, 2) when a doctor sees an elevated BG in an adult, they assume Type 2 without doing appropriate tests, 3) in many adults, the onset of Type 1 is slower than the rapid onset typically seen in young children. Also, many GPs have such limited time with a patient. But a good doctor, a true medical detective, would look at the whole picture and see the classic phenotype of adult-onset Type 1. And that same good doctor would immediately order the full suite of autoantibody tests + c-peptide.


Yes, but doctors frequently claim that autoantibody testing is too expensive. Even the American Academy of Family Physicians (AAFP) discourages performing autoantibody testing! Contrast the low cost of autoantibody testing with the very high cost of DKA due to misdiagnosis, or the cost of rapid onset of diabetic complications.


C-peptide only in mid-normal range combined with very high blood sugars is abnormal. Type 2 should see high c-peptide and high sugars. Low or normal c-peptide with high sugars should raise questions on insulin deficiency. We only learn this in retrospect…

A bit more info: And (and a least for me as a T2) When one is well controlled your C-peptide numbers return to the mid range.

I was mis-diagnosed as type 2 in 2014 by the VA. I took their pills (metformin, etc.) and it did nothing.
I did a ZERO CARB diet, not much better!
I ASKED to be tested more. She said it didn’t matter and didn’t apply to me.
I found VA Choice that lets me use a private doctor in 2016.
My new endo, within 5 MINUTES of talking to her, told me that I was Type 1. I had every sign, fit everything from JUST TALKING to her!
The tests proved it. Slow onset type 1. Low C-peptide, anitbodies and and A1C of 7.5 (again, eating VERY LOW carb, like 5 to 30 carbs per day.)

The odd part is that VA is known for going overboard on testing. And even after I ASKED, they refused because it ‘didn’t apply to me.’

I could have just cut-and-pasted your message… I was mis-diagnosed at the age of 45 (8 years ago) and was continually told by my Dr I was Type 2 and “we are treating it with medication”… I’m 6’-1", 155 lbs and exercise 5 days a week… My A1c had crept up to 7.9… After demanding I see a specialist I was told in the first 5 minutes of my first visit that I was Type 1… I have to say I was relieved… I’ve been on Insulin for about 4 years now and latest A1c was 5.6 :slight_smile:

Thanks, Paul

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I am always amazed with the stories I hear since I was diagnosed with diabetes. When I first noticed symptoms- weight loss, frequent urination, blurred vision, and thirst— I was scheduled for annual labs before a physical. BG 350 and my doctor said type 2. Within 48 hours my husband and I knew I had to go to ER. Next was 8 hours of fluids, still no insulin until shift change. Then I was rushed to ICU with official diagnosis of DKA which I had all along and stayed there 3 days. I am sure I would have died if I did not go to ER. So I had type 2 diagnosis for 48 hours. I was 60 years old then. The Endo ran multiple tests to confirm. What is wrong with these doctors? I am a doctor myself and I just could not believe it.