Need to figure out what type I am. Lean, HBA1C 6.1, no antibodies, low morning insulin/C-Peptide

I already started a thread about my question in a different subcategory, but there I am asking about what treatment to try out. Lean, HBA1C 6.1, no antibodies, low morning insulin/C-Peptide. Now what?

Here I would like to figure out what test to ask for next:
35 y.o. male, physically active, Height: 5’ 9.5", Weight: 143, BMI: 20.5

HbA1C: 6.1, has jumped around between 5.7 and 6.1 for the last 3 years. Official diagnosis is preD, obviously, but I agree with some posters here that the distinction between preD and frankD seems quite arbitrary.
Morning BG: almost always between 80 and 100.
2 hr pc bg: between 130 and 140 unless very precise about my meal. My Endo says 140 is higher than what he would like to see.

TSH was tested, and it came out a 1.37 in the range of 0.4 - 4.5.

Everything in my comprehensive metabolic and lipid panel was in the normal range, except for fasting insulin:

Insulin is 1.6, low, where the normal range is 2.0 - 19.6 uIU/mL. As an aside, C-Peptide came out as 0.91 for a normal range of 0.80 - 3.85 ng/mL, so within range, but on the very low side.

Significant history of diabetes in the family. At 40, grandma was diagnosed with full-blown insulin-dependent D, which means that she’s been preD for many years before, so similar to where I am now. She had many brothers; many of them ended up blind and without legs; everyone was by and large lean, and most diabetes diagnoses rolled in around 40, so even though I am at HBA1C 6.1 right now, scary things are around the corner if I am not proactive.

Now, I’ve been reading around, and thin + around 40 + low morning insulin starts looking like LADA for a lot of posters here, so I requested the AB panels from my endo. He’s cooperative, so I got them. I got three tests: GAD65, “ISLET CELL ANTIBODY” and “INSULIN AUTOANTIBODY”. They all came out negative.

As another aside: I am writing them out instead of using the abbreviations because I am confused about the many abbreviations - they look a lot like each other. For example, I would’ve thought that “ISLET CELL ANTIBODY” is “ICA”, but for some reason the lab (Quest) encoded it as “IA-2”, which I thought stood for “insulinoma-associated (IA-2) autoantibodies” (from ). Anyway, I am trying to figure out the precise details of the antibody encodings with my endo.

I bought the 23andMe test back when they were offering the Health Risks service, and for many D genes, I have the genotype that is associated with higher incidence. The three with the highest contribution seem to be: TCF7L2 Genotype CT, CDKAL1 Genotype GG, HHEX Genotype CC. These are associated with “impaired baseline insulin secretion”, “impaired first-phase insulin secretion”, and “decreased beta cell glucose sensitivity and 30-minute insulin response” (just copying this text from 23andMe)

Anecdotally: when I was a child I was always very thin, and have always had problems putting on muscle mass and keeping it. I now wonder whether this is because my insulin response was always under-performing.

With all that background information:

What test should I ask for next? I am still waiting for results on a Vitamin D deficiency test, but am at a loss as to what has the highest probability of giving me more information.

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Sounds more like Type 2 than LADA or Type 1 to me based on all the negative antibody tests. I could be wrong. Other opinions?

I have to say, I have struggled forever trying to get a specific diagnosis for my diabetes. With no success. Type 2 diabetes means “diabetes of unknown cause.” That is what you have. You have been given some suggestions on what to explore. Maybe you will find a specific diagnosis. But chances are you won’t. I never have. And in the end, it actually doesn’t matter. What really matters is that you find a treatment that works for you to enable you to lead a long, happy and healthy life.


Because insurance reimbursement is better for Type 1 diabetes (pumps, CGM’s, etc.), I always encourage people to try to get the “right”'diagnosis. However, as Brian says, I don’t think that there is true understanding of how many types of diabetes that there are. No matter what your type is, just be sure to fight for appropriate treatment!

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I agree that in a certain sense it doesn’t matter: I have something, and if I figure out how to fix or manage it, it doesn’t matter what I call it. That’s certainly true. There are other senses in which what I (or the doctor) call it most certainly matters.

For example, I am lucky enough to have health insurance. They will cover the cost of a CGMS for a LADA or Type 1 who has been on insulin for 6 months. The conditions under which they would a Type 2 are unclear and rare. As you pointed out in the other thread, I’ve been having a hard time catching when exactly my BG spikes, so I could benefit from a CGM. Am I ready to spend $1K + 300/mo out of pocket for something that could be covered?

That’s exactly my point, we posted it at the same time!

At this point in time, I think it’s going to be pretty difficult, if not impossible, to be diagnosed with Type 1 or LADA (which is also technically Type 1), as your C-peptide is WNL (within normal limits) and your antibody panel is negative. Do you believe you have LADA/Type 1, and if so, why?

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I don’t think I ‘believe’ I have LADA/Type 1, but what I do believe is that we have not ruled it out.

To start with, there’s a decent number of posts even on this site that argue that a negative test for antibodies does not allow one to rule out Type 1/LADA, for example, here:

When my low morning insulin came in, my endo said “that result makes me think a bit. You are not what we think of as a ‘typical’ Type 2: someone who progresses from insulin resistance to insulin deficiency. You are insulin deficient right of, and have no sign of insulin resistance”.

I understand that I am not Type 1 from the view that “Type 1 requires complete or near-complete absence of insulin deficiency”.

I understand that I am not LADA from the view that “You should have antibodies and a low C-pep”. By the way, though my C-pep came in as 0.9 where the cut-off is 0.8. When it comes to diagnoses, I believe that the cutoffs should be looked at as “fuzzy”, because that’s how the studies that determine the cut-off work. They say “well, looks like 66% of people with the disease are below this number, so that’s the cut-off”.

Brian mentioned a few times MODY as a possibility. I will look into that next.

Exactly right. I started out as a diabetic (not Type 1 or Type 2). Metformin and Lantus alone worked well for fifteen months. Then the honeymoon ended and my A1C went up to 10.something %. THEN they decided to test for antibodies. By the time my night of fasting was over, I personally didn’t need the test to verify it for me. I felt like death warmed over. I was shaking and quaking all night into the morning.

The important thing is to find a treatment that works…and if it stops working make a lot of noise until your doctor helps you find a treatment that DOES work.

Once you have all the right tools, then you’ll get to the point where you can figure out yourself (guided by a good endo) when you need to change what you’re doing. You’ll also know how to test to figure out what those changes should be.

I think the sad truth is though that, as you mentioned, your °1 reason to find out is for insurance reasons (which is understandable). But since insurance will only accept an antibody test as a confirmation of T1, even if you are T1 without antibodies, it won’t help you as you will not be recognized as T1 by your insurance and hence have no benefits from it.
so, again, just finding an ideal treatment for you seems to be the best plan for the moment.
CGMs might also be available to you via your endo office, they might be able to provide you with one for a week and insurance could cover it for “diagnostic reasons”

You can catch when your BG spike by using a regular meter and test every 15 minutes beginning 15 minutes after you eat a “normal” meal with some carbs, continue testing until you’re satisfied you’ve caught the spike, probably an hour or so. You probably won’t catch the exact peak but you’ll be close enough that you’ll have a good feel for how high your BG went.
If you REALLY want to catch the peak then test more often than 15 minutes.
A CGM isn’t necessary and seems a bit over kill in your situation.


Many Type 1s still produce some insulin decades later. The idea that T1s produce no insulin is a dated notion.

Fascinating. So, not every Type 1 has antibodies, and not every Type 1 has a total absence of insulin.

You’ll drive yourself crazy looking for the perfect acronym to define your unique condition;). My advice is just to focus on staying healthy and not get caught up in the semantics… Doing so does very little good in my estimation and can cause a lot of stress and discontent.


Dr. Faustman’s work has revealed information on that very fact:

Abstract The type 1 diabetes field has held firm to the dogma
that the pancreas is no longer viable, and thus incapable of
producing insulin, within 1 to 2 years of diagnosis for the
majority of patients. A new study in this issue of Diabetologia
(DOI: 10.1007/s00125-013-3067-x), based on a hypersensitive
assay, has found detectable C-peptide, a marker of insulin production,
in individuals with long-standing type 1 diabetes. This
new study confirms and expands a decades-long track record of
research finding intact pancreatic islet cells in advanced disease.
Because the evidence, stemming back to 1902, was largely
histological in nature, it was dismissed as lacking functional
corroboration. This new study in patients with long-term diabetes
shows appropriate functioning of pancreatic islet cells after
exposure to a mixed-meal stimulus. The weight of evidence now
makes it clear that a large fraction of patients with long-standing
diabetes have low level, but persistent functioning of pancreatic
islet cells enduring more than a decade after disease onset.


I remember our having Dr Faustman here for an interview and she found plenty of long time T1Ds who still had insulin production. I may be wrong, but I think @Richard157 is one.

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There have been 1000 participants in the Joslin Medalist Study. All participants have been T1 for at least 50 years. C-peptide tests were given to every participant, and many of them were found to be producing more insulin than we would expect for T1D’s. My C-peptide was less than 0.1, so I am not one of the insulin producing participants. There was one medalist who has to lower her insulin dosages frequently, and then stop insulin for a while. Apparently her pancreas produces insulin sporadically, in varying amounts. That must be so hard to control. I bet she has to test very frequently. She probably appreciates a CGM very much! I am a member of the secret Joslin Medalist group on Facebook. Several members of the group are producing some insulin, but they are still insulin dependant. I use a total of 35 units of Humalog each day in my pump. Other people in the medalist group use as little as 12 units per day. I am a T1 with insulin resistance, so that is part of the explanation for my needing 35 units each day.


So my first antibody test was negative and my internal medicine doctor ruled out T1 on that alone (she didn’t know about the GAD and other tests that an endo would be far more familiar with). I always though that was weird since the other tests showed beyond a shadow of a doubt that I was not making insulin. But later my antibody was positive. I always thought that was weird.

I think there may be more categories of diabeties than currently available. I think there are a lot of us who fall between the cracks. I am a thin type 2, 110 pounds with a low normal c-peptide but GAD negative. My Endo didn’t run the other tests. She feels I am somewhere between Type 2 and LADA, which I don’t understand. even though my bgs have been good I have already developed several complications.

My insulin use has gone down dramatically as I have gotten older. My endo says that it is related to a slowing metabolism. I also don’t eat as many carbs as I used to. I will have my first c-peptide test ever when I get to Medicare in 2017. I assume it will be quite low, but I have the paranoid fear that it will be too high to qualify for a pump. When I told my endo that, she just laughed.

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