C-Peptide, Type 1 or 2 Confusion...does it really matter?

brief hx: I was dx with diabetes in October 2007 and I guess my doctors are still trying to figure out what type I am. My question is–does it really matter, provided my blood glucose levels are within goal?

I don’t fit the type 2 profile (age 34, active, not overweight, no family hx of diabetes). I first tried diet and exercise, but saw my fasting levels rise to an average of about 140. I then tried Januvia and Metformin, neither really seemed to do anything. Last week I started using 8units of Lantus in the morning and my fasting level is at about 100. I’m so happy to see the huge improvement. I’m still having to eat fairly low carb (no more than 30 grams per meal), but this seems manageable.

Here’s my confusion: My C-peptide started at 1.1 (fasting) and was at 2.4 the other day (when I was running a little high–around 180). What does this mean? Type 1.5 or 2? Does it really matter? Should I be happy that I am at least producing insulin? I’d appreciate any comments/advice. Thanks!

Hello! it sounds to me like you are type 1 diabetic juvenile diabetic. Age is not a factor . I was 25 years old when i was dx. I am Juvenile diabetic. You might be producing insulin because you are in your honeymoon stages. When were you first dx or tested for diabeties? Well I am not A doctor or physician my guess is type1 take care bye. diabeticidol94

You can actually be tested for specific auto-antibodies (GAD-65, IA2 and insulin I think). Granted, the non-presence of these does not necessarily mean you aren’t Type 1. Lots of people would say that as long as you are in control, who cares what type? I say no need to be taking Type 2 meds if you’re Type 1 - you could just end up wearing out your beta cells even faster. Also, if you are Type 1 and you are diagnosed Type 1, the insurance companies won’t be so quick to deny the appropriate amount of test strips or a pump.

I was 32 when diagnosed, underweight and no Type 2 in the family (didn’t know about the other Type 1 at that point) and when my doc said I was Type 2, I forced her to run the antibody testing. Apparently I was the first adult to present with Type 1 in a non-DKA state that she had ever seen. Either that or she had mis-diagnosed plenty of other folks as Type 2.

You most definitely want to know, if you are a T1 you want to stop taking the pills and go on a full basal/bolus regimen so that you can preserve what little beta cells you have left. It will help ease into full blown dependence on insulin by making up a little bit for miscalculations in your boluses. Plus like stated earlier, insurance companies treat the two differently in what they will provide.

I agree with Kimberly, you really should know because almost all type 2 medicines are of no use whatsoever in treating type 1 and some can actually be rather harmful (by increasing your likelihood of severe hypoglycemia, for example). Its unclear to me what figures you are citing with regards to your c-peptide count. The c-peptide test provides a snapshot recording of insulin production, and normal values for a c-peptide test are usually between 0.5 and 2.0 ng/mL (nanograms per milliliter). However, normal values may vary from laboratory to laboratory. Results may also be expressed in different units (e.g., nanograms per milliliter and picomoles per liter) from lab to lab, but without knowing the unit of measurements used in your test results, its hard to say whether the results are normal or not. Generally, anything lower than normal is concluded to be type 1, whereas newly diagnosed type 2 patients will often have normal c-peptide results or even much higher than normal results due to insulin resistance, but the longer someone has type 2, their counts may decline steadily to the point of being indistinguishable from a person with type 1, but that is seldom the case at diagnosis. But you might consider having the doctor do autoantibody tests to try and confirm what type of diabetes you actually have, although most doctors themselves admit that the results may be a bit “fuzzy” sometimes. But correctly assessing what type of diabetes a patient has is a vital first step in correctly treating the disease. An incorrect diagnosis can cause serious problems.

“One of the worst things that can happen is to take somebody with type 1 diabetes and then not treat them adequately,” says Alan Marcus, MD, of Southern Orange County Endocrinology in California. “That has a catastrophic outcome.”

When insulin is made in the body, it is in a pre-form that is in active. To activate the insulin, the c-peptide part of the protein is cut away, leaving insulin and c-peptide. Insulin is rapidly degraded and used, so measuring insulin levels is tricky- especially after food- because the results may be inaccurate. C-peptide stays around in your blood stream longer and is a better measure of insulin production.

You saw c-peptide in your blood when fasting (meaning despite your high numbers you are at least producing some insulin. When they measured you again when you were high, the numbers went up- because your body was releasing more than just basal amounts to bring your sugars down.
Just producing some insulin does not make you a type 2- but it doesn’t mean that you are a type 1 either- it just shows you that you still have some insulin production.

The insulin we take is artificially made- and is already active- so it doesn’t have any c-peptide in it. This is one way to tell how much insulin your body is making by itself without confusing the test with what you take additionally.

Testing for auto-antibodies is one way to help distinguish the types- type 1 diabetes is an autoimmune process- where your own body’s immune system starts attacking your beta cells, resulting in you making less insulin and your blood sugar rising. Most people with type1 or LADA test positive for them. The antibodies are not what is causing the destruction, they are just a sign of it.

However, you seem to be doing well with the treatment you are on, so it may just be a matter of semantics at this point. I doubt your endo wants to put you on more oral meds for type 2s given that they didn’t work the first time and insulin (the lantus) is helping.

Be happy for the insulin you have- if you are a lada or type 1 then it will probably progress and you will eventually need more and more insulin. However, this is not always the case- there is someone in this community who is able to get by with diet and exercise alone for over 5 years- and doesn’t seem to be progressing. Her name is Marie, I think, and she posted on the forum about that. She is very lucky.

bottom line: all is well now. You seem to be in good hands and should your condition change, you have a wealth of information at your fingertips here.

Good luck-


If you have the antibody tests make sure you have the whole panel, not just the GAD test. Some people, like me, are positive for only one antibody and although GAD is the most common, it’s not the only one. I have islet cell antibodies and some folks have insulin antibodies. My non-fasting C-peptide is at 3.4 and fasting is 1.3 one and a half years after diagnosis. The key to maintaining some insulin production is to keep your BG as normal as possible.

Thanks for all the advice. Just hearing from everyone about their experiences and understanding of diabetes makes me feel a little less alone.

I am seeing an endo and have stopped all oral medication. The lantus continues to be giving me good results, so where I go from here…only time will tell. I will, however, talk to my doc about the antibodies tests during my next visit. Thanks again!

Unless you have a diagnosis of NOT Type 2, it will be extremely hard to get a doctor to prescribe insulin and if they do they’re prescribe the WRONG insulin regimens.

I went through 7 years of that and all my begging for insulin met with “NO” because they thought I was a Type 2. I had to control by eating almost no carbs, ever.

Only when I started insulin did it become clear I wasn’t a Type 2 because I was responding massively to very small doses. I could have saved myself years of grief–and a year of taking all the oral drugs–if I had had a good diagnosis.

Unfortunately, the kind of diabetes I have is rare enough that even endos don’t think of it. Or at least they didn’t a couple years ago before it got some ink in the medical press. My c-peptide is normal fasting but does not rise even after a large carb challenge–since I seem to be able to only secrete basal insulin, which is compatible with my MODY diagnosis.

It matters in term of some insurance companies. I am on Medicare/Medicaid and I was trying to get an insulin pump but because my diagnosis was Type 2, I was unable to get one. They have since done some testing on me and have discovered I am actually Type 1.5. Since that diagnosis I have been able to get an insulin pump.

Ok, so I was admitted to the hospital last year after a 605 glucose on a random test at my docs office after a friend who works in a doctors office thought that the stuff I was going through indicated I get tested for diabetes (lots of sweating, MUCH more frequent urination than before, etc)

I was insulin resistant, which metformin helped, but things also didn’t get completely under control until they had me on lantus and enough novolog before meals. Human insulin wasn’t working fast enough.

But I’ve never had all the anti-body tests. Barring those test results, what does that sound like? type 2 and type 1? this was all when I was 36 years old last year. 3 of my 4 grandparents have type 2 in the family, with a few more distant relatives with type 1.



type1a is an autoimmune disease,type1b in non autoimmune disease and both are insulin dependant.
you are right ,it does not matter which type as long as you normalise your blood glucose,insulin is the right choice,hope it will go on like that forever


Just keep and eye on things. I also was diagnosed around age 45 first as a type II, then later as a type I, then finally as a type 1.5. I am lean and athletic. Does it matter what type you are? Probably not if you’re monitoring yourself well. You could be in the honeymoon phase of LADA and progress more towards type I as your pancreas becomes less active. I went from an A1C of 6 something to over 10 in about 4 months. I had been stable on oral meds, diet and exercise for years when suddenly and for no apparent reason, my pancreas went south. A routine A1C caught it as i was not testing regularly. Why test? I had been stable for years and I was exercising and ate a good diet. I guess it’s just part of the aging process. I’m on a pump today producing no insulin of my own and my last A1C was 7. Life has not changed much, I’m just more vigilant.

Thirty grams of carbs at one meal is high carb to me. Seriously. i cannot get a decent blood sugar eating over 9 g per meal. A decade ago it was 12. My c-peptide is normal. My weight is normal and was most of my life. I do not have any of the Type 1 diabetes antibodies. I had an abnormal glucose tolerance test when I was 28 and weighed 108 lbs. Two cases of gestational diabetes. Doctors have been utterly clueless.

I probably have MODY based on my sensitivity to insulin.

You might actually do better using fast acting meal time insulin than the Lantus. I do. If I control my meals, my fasting drops. It turns out I seem able to secrete some fasting insulin but none in response to rising glucose after meals. This is a characteristic of some forms of MODY.

Also, based on my own experience, if you start experiencing fast pulse after being on Lantus for a few weeks, you may be using too much. Some of us with these weird forms of diabetes are very insulin sensitive but also have strong counterregulation which fights lows so when we hypo we end up around 108. I was using 8 unts of lantus for a while and my fbg started to creep up, while my pulse went out of control. Turned out the right dose for me is 2 units! I saw a couple doctors and no one diagnosed the pulse problem as a hypo symptom… They thought I had a heart condition. It went away when i stopped the Lantus, switched to R insulin at meals which worked much better for me.

I can cover a meal of 40 grams of carb now with 2 units of Apidra almost perfectly.

Dear Jenny.

A bit surprised I thought that everybody gets a high heart rate when the BG goes low. amazing that your carbs to insulin ratio is so high at 20:1 mine is more like 2:1. No wonder the doctors are confused every form of diabetes is so different. Here in canada the CDA only recognizes type 1 and type 2 and gestational. Trying to loose weight to see if that will help the insulin resistance. Trying out a weight loss pill called meridia to suppress appetite. Appears to be working so far. Doing also 1 hour of exercise per day.

you are right ,since i have been on novolog insulin i feel so much better,i am on the pump and cgms and that help me with my high and lows,because i don’t feel them coming on.it does matter to know what type diabetic you are,it is important to know what type you are dealing with.i had the test done-cpeptide is 0.3,my a1c 6.2.i was told by a dietician to get in 60gm of carbo q meal and that is to much,iwill only do 30-45 per meal.insulin is the way to go.

Since Type 1 diabetes and Type 2 diabetes are two completely different diseases (different genetics, cause, treatment, cure), it seems to me to be important to get a correct diagnosis. I think the problem is that doctors try to treat adult-onset Type 1 autoimmune diabetes (also called Type 1.5 and LADA) with treatments that are only appropriate for Type 2. The remaining beta cells can be better preserved using intensive insulin therapy when an adult-onset Type 1 is first diagnosed, prolonging the honeymoon, improving control and greatly reducing the risk of complications. The definitive test for Type 1 autoimmune diabetes (at any age of onset) is antibody testing (glutamic acid decarboxylase antibodies (GADA), islet cell antibodies (ICA), and insulinoma-associated (IA-2) autoantibodies). The World Health Organization (WHO) does not recognize Type 1.5 and LADA, because they are actually Type 1 diabetes.

wow lane what a great response


lane good job,thank you.//////odessa