What Is Your (Diabetes) Type? A Guide For Those Suspecting Misdiagnosis

In my last blog I wrote about the different Types of diabetes. In this blog I will dig a bit deeper to create a scorecard so you can see how ‘typical’ you are and, if you are Type 2, give you a way to see if there is a possibility of misdiagnosis.

I am going to ‘borrow’ an idea from “Think Like a Pancreas” and have a tl;dr section at the end. If you want a quick summary to see if it the blog is worth the time to read, you know where to go.

The Prevalence of Misdiagnosis

Why am I so passionate about the possibility of misdiagnosis? Because it happens a lot. It is estimated that approximately 80% of MODY/NDM diabetics are misdiagnosed as Type 1 or 2. For LADA, misdiagnosis could be as many as 20% of Type 2s, and one study of 2 million diabetics showed that 97% of the Type 3c diabetics had been misdiagnosed as Type 2.

Why is it important? Because treatment, while not defined by Type, is informed by it. For MODY/NDM, the insulin production machinery is broken on a genetic level and for different gene mutations, the most effective treatment is well understood. Trying generic Type 2 treatments will, at best, be as effective but more likely be less effective. For Type 3c, the physical damage to the pancreas means alpha and beta cells are damaged and so it is not just insulin production that is affected. Treatment should account for this. For LADAs, drugs which work the pancreas harder, while appropriate for Type 2s will destroy the pancreas’ beta cells quicker and make the patient insulin-dependent so much quicker.

From a patient’s health perspective, a poorly targeted treatment means blood sugar control will not be managed as well as it could, leading to a higher risk of long term complications. Misdiagnosis is unfortunate for the doctors but can be devastating for the patient.

The Practical Diabetic’s Type Scorecard

Based on key parameters, it is possible to put together a simple scorecard to steer a clinician towards an appropriate diagnosis. I will focus on Type 1, Type 2, LADA, Type 3c, and MODY/NDM simply because Gestational diabetes is routinely tested for and Type 0 presents very differently to the other Types and is more easily diagnosed. I will also assume, like many of us, the patient has presented with a mild DKA for the first time e.g. thirsty, peeing a lot, lethargy, losing weight etc. so we are at the start of the diabetic journey.

For the purposes of the scorecard I am defining LADA as a Type 1 who still has sufficient insulin production to not be insulin dependent. A Type 1 who requires insulin to remain healthy is, for all practical purposes, a ‘normal’ Type 1, possibly in honeymoon.

The idea is to work out which columns result in a positive score and then get the appropriate definitive tests done.

Type 1Type 2LADAType 3cMODY/NDM
Young (<25)+1000+1
Old (>25)0+1+100
Low C-Peptide+100*+10
History of pancreatic
damage
000+10
First degree relative0+100+1
Insulin resistance0+1+100
TOTAL SCORE

(*) Some links characterize LADA as having a low c-peptide. From my perspective if you are a Type 1 with a low c-peptide to the point you need insulin, you have transitioned, from a treatment perspective, to a (possibly honeymooning) Type 1.

After my first article I got a lot of requests for the sources of my information (a good fraction of that piece came from “Think Like a Pancreas” and “Dr Bernstein” with NCBI and Google searches to fill in the gaps). Given this article could well end up in the face of someone actually qualified in medicine and you may need to fight for that definitive test, I’ll quote my links here:

LADA Characteristics
Some More LADA Characteristics
A paper on LADA and Insulin Resistance
MODY Characteristics
Type 3c Characteristics

These are all from NCBI. NCBI is a collection of peer-reviewed medical papers from around the world and cannot be easily dismissed by a health professional.

Hopefully the terms in the first column are relatively self-explanatory. C-peptide is a measure of your body’s insulin production and obtained from a blood test. “First Degree Relative” means a first degree relative who has some form of diabetes. Insulin Resistance can be determined by examining a patient’s HOMA-IR score (derived from their fasting blood glucose and endogenous insulin). Endogenous just means made by their pancreas as opposed to injected.

So let us run it for a sample patient. In this case I will choose me, two years ago when I first presented with DKA. You can read a bit about this in my About Me blog post.

Type 1Type 2LADAType 3cMODY/NDM
Young (<25)+1000+1
Old (>25)0+1+100
Low C-Peptide+100*+10
History of pancreatic
damage
000+10
First degree relative0+100+1
Insulin resistance0+1+100
TOTAL SCORE02200

The scores suggest either Type 2 or LADA. At the time, the hospital believed I was Type 2 and sent me on my way. It was my family doctor who had the smarts to get the right tests done.

Tests For a Definitive Diagnosis

For Type 1 and LADA, the definitive test is a blood test for the auto-antibodies associated with Type 1 diabetes. In 80-90% of cases these auto-antibodies will be present in the blood. If the progression of the disease is advanced, the immune response may no longer be present making a definitive diagnosis harder.

Assuming the test is positive, the next consideration would be the c-peptide level. If it is still normal/high and blood sugars normal, it may be a case that the patient can be treated similar to a Type 2 with regular monitoring to track the deterioration of the pancreas and the transition to insulin-dependence (a slow progression suggests LADA whereas fast progression suggests a ‘classic’ Type 1). If the c-peptide is low, the best option may be to simply consider the patient as a Type 1 and treat them accordingly.

For Type 3c diabetics, a scan of the pancreas will reveal the damage and provide a definitive diagnosis. With a better understanding of the underlying pathology, treatment can be appropriately designed.

For MODY/NDM, a genetic test will provide a definitive diagnosis. As mentioned before, the optimal treatment for the common variants of MODY are known so it is easier to treat and manage the disease once it is diagnosed. This paper reviews in finer detail some of the symptoms of the different forms of MODY as well as the first-line treatments.

tl;dr

There is a lot of misdiagnosis when it comes to diabetes with many Type 2s (and a few Type 1s) being put in the wrong bucket. The right diagnosis means the treatment can be tailored appropriately to ensure the best long-term outcome for the patient.

Using a simple scorecard we can inform the diagnosis and get the right tests done for a definitive answer.

One thought on “What Is Your (Diabetes) Type? A Guide For Those Suspecting Misdiagnosis

  1. Jennifer July 22, 2019 / 4:39 pm

    Thank you! Awareness is the key #type1awareness #insulin4all #allmyblueheartsare4type1

    Like

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