The difference between type 1 and 1.5

All he stuff I have read here about type 1.5 does not tell me what is the difference really.
I mean Is it just the age you were diagnosed or is it also some pancreatic function?

I was diagnosed at 21. I don't think the type 1.5 was even used back then.

I see a lot of people here have been typed and the retyped.
It makes me think that the typing is not so clear even to the experts who are typing us.

Does anyone know what the defining issues are? It seems to me that the treatment would be the same.

Assuming that "Type 1.5" is T1 diagnosed past childhood:

I think "Type 1.5" is mostly a social term, not a medical term. It exists, because the mindset (incorrect since the beginning of time but still a prevalent mindset) is still that "Juvenile Diabetes" which then became "T1" is only for kids, so anyone else with the same disease who happens to be older needs a different term.

I think there are very real social implications that mean that T1.5's do form a cohesive group with experiences not exactly like T1's diagnosed as kids.

You'd be surprised how much age-of-patient-at-diagnosis has to do with treatment options and lots of other things.

You'd be surprised how much age-of-patient-currently has to do with the term used to describe them. I have been told many times over the decades, how I don't have "Juvenile diabetes" anymore because at that point I was over 18. (They told that to me in the 1980's when I was in college!). That my juvenile diabetes had turned into adult diabetes when I turned 18. I have been told many times as well that I'm not "Type 1" because kids have that and I'm obviously an over-the-hill grey haried adult. (Told to me as recently as this January at the opthamologist.) It's these preconceptions that make 1.5 a somewhat useful term for the recently diagnosed, because otherwise they do not fit into stereotypes.

How rude for the disease not to recognize the preconceived stereotypes of so many!

Even the JDRF has come around and finally admitted that most T1's are not kids or are not kids anymore, and they now actively support T1's who are adults, even though there's still a little bit of an asterisk on the designation to make it clear that they are "adults with T1" and not just "T1" (presumably meaning kids).

Type 1.5 is different from Type 1. Though there seems to be a grouping of a number of different types as Type 1.5; MODY, LADA, etc. With LADA (latent autoimmune diabetes in adults), the GAD antibodies of T1's are present, but there is typically a component of the T2 insulin resistance, too. This is why many people are retyped later; from T2 to LADA. And, there seems to be a longer time period from time of dx to depletion of beta cells with LADA compared to T1.

I second what Tim already wrote.

In addition I would like to suggest a different name for the disease we have or a different thinking about it. It would be better to call it "Rogue T-cell disease" or "Autoimmune disease". This disease can manifest itself as T1 diabetes. If this takes longer than usual scientists suspect there is some difference in the autoimmune response and call it T1.5. But the driver behind all that is the rogue behaving autoimmune condition we have. This is important because it takes many coincidences to actually develop T1 when we have this autoimmune disease. One important precondition is a higher alertness of the immune system. This makes it very likely that we develop T1 at younger ages. Still there is a high likelyhood that the immune system does not focus on the beta cells. With age the immune system seems to change too. Likely at some point these changes will trigger different manifestations - even the then called T1.5.

Many of us look at their families and think "oh, I am the only T1 in my family". But looking closer you will very likely find a pattern of autoimmune diseases in your family: often thyroid related, sometimes skin conditions like lichen ruber/lichen sclerosus, sometimes digestive conditions like gluten sensitivity and very very rarely T1. These conditions are all manifestations of the same underlying autoimmune condition. Because of this T1 diabetics are also more likely to develop these conditions too. The increase is small but statistically significiant.

I was diagnosed with Type 1 at age 49. According to my endo, who was also diagnosed Type 1 as an adult, although younger than me, it was not type 1.5. All of my symptoms were classic Type 1: 20 pound weight loss over about 2 months despite eating as much in one day as I normally would eat in 3, thirst, fatigue, frequent potty breaks. I was also very insulin sensitive, which he said is less likely to be the case with Type 1.5.

It would be better to call it "Rogue T-cell disease" or "Autoimmune disease".

I'm not so sure. I think that diabetes is diabetes. It might be autoimmune caused or maybe something else. For 99% of purposes it doesn't matter how it happened, what matters is our lives going ahead. But to call it anything other than diabetes would probably not help the affected get the treatment they need.

I think that as the number of available diagnostic tests has grown that we now spend way way way too much time inventing terms for the different permutations of tests "passed" and "failed.". To subdivide the categories until we feel we have little in common with other diabetics who share 99% of the same problems (but happen to have been diagnosed at a different age, or with a different combination of tests) is a big problem too. I see T1.5's or T2's who claim up and down that I'm T1 and therefore don't know what they've gone through. They have a point about our social and/or medical pasts, but going into the future I see a lot in common and a lot we can share.

My understanding is that the term "1.5" is just shorthand for T1 in adults.

Before antibody testing existed, if you were diagnosed with diabetes in childhood, you had "juvenile diabetes" (aka, "the bad kind") and if you were diagnosed as an adult, you had adult-onset diabetes. But once testing got more sophisticated, they were able to differentiate between what we now call T1 and T2.

An endo once told me that when adults develop T1 or any other autoimmune condition, it often comes on more slowly than it does in children, and that different presentation is what leads to many misdiagnoses (we asked because I have a sister who, while not T1, has been told she has as much as a 25 to 50% chance of developing T1D at any point in her life, regardless of age).

There are also a not-insignificant number of people who seem to fall into a "diabetes gray area." They don't have antibodies, but don't fit the general profile of a T2. These folks tell us there is still a lot we don't know about diabetes, and for them, the term 1.5 may be more appropriate.

Please be assured that I do not really meant to call it differently. My intention was to change something about the way we see this disease. Perhaps there is no T1 gene at all. It might all be just a statistical experiment with an autoimmune disease / flaw as the root cause and different possibilities for manifestations. This can be considered more unifying than dividing - at least I hope so.

I know it's very easy for me to sit around and do armchair quarterbacking and invent new diagnosis criteria that divides all of us into diagnosis groups of one based on a zillion different factors. I know that I've done such hypothetical division and subdivisions in the past.

But those actions seem kind of self-defeating if the goal of tudiabetes is to unite all of us based on what we have in common. Diabetes! To start calling what I have, other than diabetes... wow, that's really drawing a line in the sand. I'm not sure I really want to see myself as different than any other diabetic (Type 1, Type 1.5, Type 1.734323434, Type 2, Type 3, LADA, MODY whatever) here.

It also seems self-defeating for the medical establishment to subdivide us too finely based on a zillion different tests, if we are to be given access to the useful resources and tools we need to control our diabetes, and most of those tools are the same no matter what tests we've passed or failed or invent in the future.

Type 1.5 is not a medical term, and is not included in the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus's position paper. The problem, as Tim says, is that there has been a "head in the sand" denial by the medical community that Type 1 diabetes occurs at all ages. There really do seem to be different life impacts if you are diagnosed as a child versus an adult, but it is still the same disease. I think it should just be called autoimmune diabetes (autoantibody (GAD, ICA, IA-2, Zn8, and/or T-reactive cell) positive) instead of these silly, meaningless numeric terms. And yes, the treatment is the same: all people with autoimmune diabetes need to be treated with exogenous insulin. As for people being re-typed, if appropriate testing were done at diagnosis to distinguish adults with autoimmune diabetes (autoantibodies, T-reactive cell) from those with Type 2 diabetes, there would not be this re-typing problem (and the problem of mistreatment). Type 1 diabetes/autoimmune diabetes is not a childhood disease!

1 Like

I had no idea there was such a fight in the med community about the variant names of diabetes! Granted, I haven't exactly paid a lot of attention over the years,,,

In 1982 at the age of 23 I was diagnosed with what my doctor referred to as late onset juvenile diabetes -- not Type 1, 1.5, 2, etc. Seemed pretty clear to me, and there were no arguments about it. I immediately went on insulin, and that was that.

That is still what I call it, though I've also taken to calling it Type 1 since that is the term that layman tend to know out there.


Just to give my two cents: I prefer the term LADA (Latent autoimmune diabetes in adults) I dislike the popular term "Type 1.5" because it implies it is halfway between Type 1 and Type 2. It is not. LADA is type 1 - it is as the term says "autoimmune diabetes) that occurs in adults. However age is only one difference of LADA from "traditional type 1". The more important difference is the "latent" part. LADA does not come on all of a sudden, landing people in the hospital with DKA. The beta cell destruction is more gradual. So people like me, (I was 58 when I was diagnosed and I did fine on oral meds for 15 months) are frequently misdiagnosed as Type 2.

Now, nearly 5 years in from my intial (mis)diagnosis, and three years since I got my correct diagnosis and started insulin, I just think of myself as a Type 1. My disease looks and acts like any other Type 1. I usually just say "I'm Type 1" unless there is a reason to explain further. So do I think the LADA distinction is important? I absolutely do. For the reasons Melitta suggested. People are still being misdiagnosed. If LADA raises the awareness that a person who is an adult or even middle aged at diagnosis should be tested for antibodies - especially if they have other markers, such as normal weight or extreme weight loss, other autoimmune disease, need for insulin earlier than typical with type 2, and insulin sensitivity.

My understanding is that "type 1.5" or LADA is simply a very slow version of the same dysfunction that leads to type 1. It's an autoimmune attack on the pancreatic beta cells, it just doesn't happen anywhere near as fast as it does in standard garden-variety T1. Which means that the person with type 1.5 has a fair amount of time where they do not need exogenous insulin (or maybe, they don't need as much insulin) to keep BG levels in normal range, but eventually, it becomes T1 in the end. The studies of drugs and therapies intended to reduce the autoimmune activity and quiet the immune response might change that down the line so that individuals with LADA have the ability to stabilize, if not halt, the autoimmune response and maintain functional beta cells. With standard T1, it usually happens so quickly that by the time you figure out what's going on, the beta cells are mostly kaput.

Here this should help confuse the matter even worse. Check out this medical study done about LADA. LADA IN TYPE 2

That they have found 14 LADAs in the group of 74 people diagnosed as T2 is no surprise. For me the surprise is more that they do not conclude that these people have been misdiagnosed. But the functional problem these patients are facing is T1.5 not T2. Some of them may have a combination of T1.5 and T2 (insulin resistance) but the treatment needs to be focused on T1.5 to prevent serious complications like DKA. The study has a strong message: 18% of the people diagnosed as T2 might in reality be T1.5. In respect to the sheer number of T2 this high rate is really concerning. I wish they would have concluded the same.

and then I just found this interesting read about LADA diagnoses.

Dr. Bell's 2005 LADA article has some inaccuracies that make it not really applicable, I think. First, if you just test for GAD in a suspected LADA, you will miss those who are only ICA or IA-2 positive. So the full suite of antibody tests should be run. Then, Dr. Bell does a lot of "backflips" to say that LADA (autoimmune diabetes) is somehow different than Type 1 diabetes (autoimmune diabetes). A bit too much hair-splitting. For example, I never see doctors trying to kick people with idiopathic (not autoimmune) diabetes out of the T1 club, but doctors frequently try to say LADA is somehow not in the T1 club.

Hi Holger: Very good points. A key problem that I see with misdiagnosis beyond the possibility of DKA is that other diabetes complications (retinopathy, neuropathy, kidney disease) also occur much more rapidly. For example, I was (mis)diagnosed at age 35. I went only one week misdiagnosed, because I figured out what was really going on and (after a bit of head butting) got my endo to correctly diagnose me and put me on exogenous insulin (I had been given insulin when I was hospitalized in critical condition, but then was taken off of insulin). Other adult-onset Type 1s that I know who were (mis)diagnosed at about the same time as me, 17 years ago, went for much longer periods without exogenous insulin. The tragedy is that every single one of those others now have complications, and I do not. Not a scientific study, but experiential.

True for the antibody testing from what I have read so far and I don't doctor jump so I am not sure about the "frequently try to say LADA is somehow not in the T1 club." but this is still an interesting article.

My problem was convincing my Endo to do the GAD and C-Peptide. That sounds strange but he is just so sure I am LADA that he doesn't need it I guess. But I told him it was for my own knowledge and not to second guess him and he has now ordered the tests.

we could all hope for a day when you just go get the DIABETES TYPE TEST and be done with it. Or even better a CURE so we don't have to know what type we are. But until then all I can tell you is that if I don't use insulin my numbers go up so until I have to prove something to my insurance I guess the testing is just for me to be sure of how my body is working right now. If my C-Peptide and GAD are goofy then it is just proof. If they are "NORMAL" then I will scratch my head and do them again later down the road.... now I am just rambling Sorry.. Anyway, good point Melitta but also it was a 2005 article.

Hi Melitta,

Thanks for your example of the difference in outcome for you as compared to the other Type 1s and their complications! It's a great "real world" example of why exogenous insulin is so important!

It's especially helpful to the group of us who are recently diagnosed and grappling with the "when to start insulin" question, and also for newly diagnosed Type 1s whose doctors put them on oral medications.

Thank you!