Insulin Pump and C-Peptide and GAD 65Tests

I have been what I thought was a Type 2 diabetic for 8 years, but was always treated by my internist. I now have an endo and the question has come up whether I’m a type 2 or type 1.5 because I progressed to insulin within 2 years of diagnosis. I started using an insulin pump 3 months ago and love it. Now I’m suppose to have a c-peptide and GAD-65 test due. Does anyone know if it’s okay that I’ve been pumping insulin in? I don’t want the test to show the insulin from the pump like its my body making the insulin. The endo didn’t tell me to stop the pump before the test, I’m just curious and I certainly don’t want to “waste the test” or get incorrect results because of my pump. This may not be the right place to ask the question, but of course my doc’s office is closed today and I’m suppose to go to the lab this morning. Thanks for your help

You will be OK with the pump - it won’t affect the test results. I had to get the c-peptide before I could get the pump and I asked that question because I knew I would be very, very high if I tried to stop insulin. I even Googled it to make sure that the c-peptide would not be thrown off by injected insulin & it won’t be.

Thanks the quick response. I was taking my shower this morning and thought about it. I’m sure my endo would have told me something, but she kind of ordered the tests on the fly so to speak and may not have thought about it. I hope you have a wonderful Christmas.

The c-peptide is produced as a by-product of your body manufacturing its own insulin. The insulin you inject has no c-peptide in it. So injecting insulin has no effect on the test at all. If the test shows you have c-peptide, it means your body is producing some insulin on its own but not enough to keep you from being diabetic.

You are welcome Carman! I hope that you have a great Christmas also!

Good luck with your tests, Carman. I’m glad you’ve gotten the right treatment, regardless of what your diagnosis turns out to be! When I progressed to needing insulin within about 15 months of diagnosis I did a lot of research and guessed correctly that I was LADA/Type 1. But just those few years have made a difference in how much information is out there about LADA.

I thought about this a lot for myself. @ the time, it was, and still is an expensive test for me. I think that regardless of whether I was type 2 or LADA, the bottom line is, i'm insulin dependent. Even If I was a type 2 with dead beta cells, I'm still insulin dependent. In my particular situation I thought it was pointless to get this test. Although I eventually DID get the test, I ran into other problems in terms of different opinions as to what was considered a low C-peptide count..

Please don't mistaken my above statement as a discouragement. It was just how I felt at the time.

Well, 1.5 or not, as you I am insulin dependent and my endo does say that my body is functioning as a Type 1 after do many years on insulin. This also came up because even though I’m not real close to Medicare age, I’ll be 59 in February, it’s my understanding that Medicare won’t pay for pump supplies if you aren’t Type 1 or 1.5. So, on the chance that I really am 1.5, we need it documented. Plus, if not, she will run the test every two years to show the progression of no insulin. It won’t change my treatment plan or how I feel about the disease.

Oh, ok… That’s interesting though, because, if it turns out that your type2, and have very low insulin production, and if the pump is more likely to be a necessity, how will they code that? Damn, I really do hate insurance companies, HMOs & Medicare, they make it so damn hard to get the simplest things we need. It’s always a monopoly

Carmen, you took the words right out of my mouth! If someone wants to be on MDI, then the c-peptide doesn’t matter and what someone wants to call you doesn’t matter. If you want to have a pump and be able to keep it when you go on Medicare, then it will matter.

I am on Medicare because of being on disability. After 26 ½ years of being T1, I had to get a c-peptide test in order to get the pump. I was very nervous because when I was Googling the requirements, I read on several messages boards of people saying that they had been told they were T1, had been on a pump for years, but then did not qualify under Medicare. It is not just being able to get the pump, but you have to get insulin for the pump differently under Medicare and the pharmacy had to have a copy of the c-peptide test. I changed supply companies and they had to have a copy of the c-peptide test. Even having a pump before you go on Medicare does not mean that you will be able to use it once you are on Medicare unless you have the money to buy stuff out-of-pocket.

As far as Medicare goes, it doesn’t matter what she is labeled. As long as she meets the c-peptide requirements, then it won’t matter. Actually, type is not even mentioned in the Medicare guidelines. It is in Section 204.14 starting on page 116. She would have to meet either criterion A or B plus the c-peptide. B is already being on a pump, so she meets that part.

Well, I got the c-peptide results back…1.3 is within the 0.8 to 3.1 range. I haven’t gotten the GAD back yet. I’m guessing if the GAD is within range and the c-peptide doesn’t go down within the next six years, I won’t be wearing a pump after retirement. That is, unless things change in the regulations which is always possible. Of course, it’s also possible there will be no Medicare when I get to it, lol.

Carman, do you know if your c-peptide has gotten lower? I have heard that is common. I will keep my fingers crossed for you that you get to keep your pump when you retire. I guess the other option is to just never retire (just kidding!). At the rate Medicare is going, who knows what will happen.

Actually, this is the first c-peptide test that I've had run. My internist always assumed that I was Type 2 and didn't do any further testing besides bg and a1c. I'm sure we'll redo the test on intervals to see if it goes down. I'm sure I won't retire, lol, they'll just find me hunched over my desk, lol

Maybe you said that before & my memory is not what it used to be! I feel funny saying I hope that it goes down but I think you know what I mean! I think the Medicare rules for pumps are stupid and you shouldn’t have to worry about keeping something that helps you. Hopefully they at least give you a pillow to put on your desk!

We will just hope for the best. It’s a good bit of time until I really have to worry about it. Also, what I’ve read places is that with Type 2, the c-peptide is usually high. I don’t seem to fit that picture either. Go figure.

I kinda of thought with typical T2 the c-peptide is higher but wasn’t sure. Yours seems low enough that it should go lower, but what do I know! I never had one before this summer when I went to get my pump.

Type 2’s can have either normal range or high c-peptides. Type 1’s and LADAs are low.

Thanks Zoe. We were hoping the reading was low enough that I would qualify for LADA. The GAD 65 that I did isn’t back yet and from what I’ve read, there’s also a chance that the c-peptide could drop more during the next years before I reach Medicare age. We’ll just have to wait and see.

A lot of talk about Medicare rules for C peptide. Be aware that it is not only M,edicare. In Michigan Blue Cross Blue Shield now follow Medicare rules. Both my wife and I are using pumps (19 years for me and 3 for wife) Neither ever had a c peptide before, but now just to get the infusion sets, BCBS is requiring the c peptide. I really hope they change the rules, as even for type 2’s the pump is a wonderful treatment. Before the Pump, my wife was routinely being taked to the Hospital for low Glucose levels, With the use of the pump, these episodes have been eliminated. It seems silly to have rules which keep effective treatments from people that need them