So these tests weren’t a thing when I was dx’d back in 1983, neither was antibody testing. I recently went on Medicare and I now have to show a C-pep test to prove—AFTER FORTY YEARS WITH THIS GODFORSAKEN DISEASE—that I’m actually T1. I actually did get a c-peptide a few years ago and it was 1.8, which won’t qualify, but it was not done while fasting, so I’m going to have it done again and hope for the best. I’ve long known I produce some endogenous insulin, so who knows.
Thoughts on how to get it as low as possible? I’m planning on early a.m. before eating anything.
I had a GAD antibody test a few years ago too, but it was negative, which I gather is also not a huge surprise 30+ years after dx. So that fallback isn’t going to work for me either.
What recourse do I have if refused? Letter of necessity from endo? Has anyone else successfully done this? I’ve been on a pump for ten years!
Emotional support here. This is just ridiculous and I too would be very angry and quite devastated to have to prove that I am a type 1 diabetic after all of these years. Do they think that you take insulin because you enjoy it? Do they understand diabetes at all?
Having to jump through hoops is beyond frustrating. I am so sorry that you have to do it. Take a breath and do what they are requiring you to do even though it makes no sense. Put this behind you as soon as you can.
Fasting will help, and may get you “in range” for lower number. Maybe avoid carbs the night before too.
I had to have mine tested, when switching insurance, 30+ years after being dx at age 5. Another year until I hit MC, but assume I will have another test too.
I may be wrong, but my understanding is that if you use external insulin, your endogenous insulin will not appear. No endogenous insulin? Then there is no c-peptide. My last c-peptide was done 20 years agoand it was usable for Medicare purposes. I suspect that I, too, still make some insulin. As to the GAD65 being negative, that is to be expected after all those years. Could you have some ofo the other antibodies tested? Maybe they will show up. Wish you success!
What about things to increase insulin sensitivity so whatever beta cells you’ve got left don’t want to work so hard. Like in addition to fasting before the test, increase exercise and eat low fat for a few days?
Diabetes fascinates me in how different it can be. I’m shocked (and jealous! LOL) you’ve still got any endogenous insulin.
@MM1 I could be wrong, but as long as the C-peptide test is in your records at the qualifying levels, you won’t need another test. They just used my previous tests in my medical records. I remember my endo handing me a copy in a protective cover and saying this is my gift to you to make sure I keep it. That she had made the mistake of being diagnosed when she was younger and not keeping a copy and had to take the tests again to prove she was a type 1 when she moved.
I think with so much being computerized now, that’s probably not as much of an issue. But I think you don’t have to retake the accepted tests as long as there is a record of it.
I’m so sorry you have to go through this nonsense! I went on Medicare two years ago about 14 years after diagnosis and I still produce some endogenous insulin. Maybe the folks at Joslin did a C-peptide that I didn’t know about but I was never asked for one when I went on Medicare.
@DrBB It took me forever to find the Medicare requirements for insulin pump coverage. I even looked in the 2023 book, but it was not helpful. I found the following.
In order to be covered, patients must meet criterion A or B:
(A) The patient has completed a comprehensive diabetes education program, and has been on a program of multiple daily injections of insulin (i.e. at least 3 injections per day), with frequent self-adjustments of insulin dose for at least 6 months prior to initiation of the insulin pump, and has documented frequency of glucose self-testing an average of at least 4 times per day during the 2 months prior to initiation of the insulin pump, and meets one or more of the following criteria while on the multiple daily injection regimen:
(1) Glycosylated hemoglobin level(HbAlc) > 7.0 %
(2) History of recurring hypoglycemia
(3) Wide fluctuations in blood glucose before mealtime
(4) Dawn phenomenon with fasting blood sugars frequently exceeding 200 mg/dl
(5) History of severe glycemic excursions
(B) The patient with Type I diabetes has been on a pump prior to enrollment in Medicare and has documented frequency of glucose self-testing an average of at least 4 times per day during the month prior to Medicare enrollment.
Type I diabetes needs to be documented by a C-peptide level < 0.5
“Type 1 diabetes needs to be documented by a C-peptide level of <0.5” is interesting to me as a type 2 on a pump covered by Medicare Part B. I don’t see anything about type 2.
I’m not sure, but I think doing a 12 hour fast before the C-peptide test might be helpful. Also, paying attention to your blood glucose levels (as if you wouldn’t) and keep it as close to the normal range as possible with injected insulin.
The only other thing I can thing of is an insulinoma, an insulin secreting tumor. They do secrete proinsulin, so besides insulin there would be C-peptide.
My dad just got on medicare this year and he mentioned having to get a C-Peptide test to get his pump supplies approved. I guess whatever his test result was in the range they required.
I’m sorry your having to deal with this, I’m sure I’d be very upset.
After 47 years I had this testing. I told my endo I was excited to have it done. I mean who knew, maybe I did not really have diabetes. Well damn it, I was diagnosed all over again.
Just so you know, your c-peptide test for Medicare must be accompanied by a fasting BG test. And your chart (lab results) have to say that it is fasting.
Like many people my first c-peptide test was when I went on Medicare. I passed since my result was low enough to get pump supplies. I failed since I got the lowest possible result.
Good luck on your test. Hope you get the result that your need.
My situation is the result of trying to change to a different DME supplier (from Edgepark to Wellstart). For whatever reason Edgepark never asked for a c-peptide result since I went on Medicare a year ago. The test I do have in my records is above what Medicare allows. When I expressed my concern about this to my original Endo she just said “don’t worry about it.” So I dunno. I may just try going back to them (Edgepark), but the complication is that I’ve changed Endo’s because of moving 2.5 hrs away from the one who’s down as my prescriber with them. So I have to switch that to my new prescriber and hope they just go with whatever records they already have on file. I guess.
The one big question I still have: Is there any recourse if you get turned down? As I said upthread, my GAD antibody was negative (35 yrs after dx) so I don’t have that fallback.
It’s been 11 years, and rules do change, but when I went on Medicare no c-peptide test was required. I was continuing with both the same supplier (CCS Medical) and endo, though. The test had been required when I originally started a pump, though, but with both another supplier and another endo.
I was in an NIH study back around the turn of the century, (islet transplant – no I never got one,) and they required the c-peptide test at admission to the study and then repeated every 6 months. Lo and behold, after 4 or 5 negative tests, I got a positive result, and was kicked out of the study. (The study used c-peptide as a measure of success of the transplant – I could have been considered a partial success if I had already gotten the transplant! ) That was after about 47 years of diabetes - I read later about occasional insulin production happening to other long-termers during periods of very good control: with the prospect of a possible cure, I had been very, very motivated to minimize any damage from high glucose.
Be prepared - Medicare messed me up last year ( delaying my pump supply orders) by requiring me to have a C-peptide test. I am now 72,so I have been on Medicare for 7 years. I called Medicare, and they told me that it is now a Medicare requirement that c-peptide is to be done YEARLY in order to get our pump supplies! RIDICULOUS! As you said, do they think we do this for FUN?
The first thing a Doc should offer to do is write a letter of necessity. I’ve never had a letter of medical necessity refused. Docs use those when insurers ‘act out.’ The insurer has no standing because they are not a doctor. They are not allowed to dictate how care is provided - only a doctor in charge of your care is. I assume that your Doc is providing care because they actually believe that you are a diabetic. Doctors diagnose, not insurers.
Often when I do lab work for me, I tell them to take into account (when evaluating the results), that I am NOT fasting. T1’s can’t be assumed to be fasting. This is an interesting T2 problem and I’m glad you brought it to attention.
I would call ADA. They have great advisors. You might also consider calling DPC (just to at least spread word that this is an issue).
I went through the same thing last spring. I was on MDI for 45 years using Novolins, diagnosed in 1977.
A letter of medical necessity won’t get Medicare to waive its policy but the diagnostic criteria they use are pretty lenient. If you’ve had hypo when you haven’t grossly overdosed and you have a good handle on your ICR and CF, you shoud be able to pass the test.
Medicare will reject a C peptide test if your fasting BG is above 225 mg/dL. That should be easy.
Ideally your fasting BG should be between 100-120mg/dL so there would be no doubt that the test wasn’t accurate - if you were in honeymoon stage. But you aren’t. My endo pushed me to get mine under 100 . Normally my morning rise is enough that if I’m at 110 at 4 am, by 7am I’m at 130. So I ate a smaller dinner with more protein and fat. I was at 100 when I woke, went straight to the lab. By the time they drew blood I was hypo. Which caused me to fail *my endo’*s criteria
The second time they just said to get it below 130. I just waited without eating that day until my BG had dropped low enough and took the test.
In the absence of renal insufficiency, insulinpenia is defined by a cpeptide value less than 110% . With it the value has to be below 200% of the lower limit of normal of the labs measurement method
From my experience I believe the easiest way to get though this would have been to start with a personal CGM sample and get my nighttime control stable before I took the test. Within a week of using my CGM without a pump I had my nighttime BG nailed.
If you consistently have difficulty getting your fasting BG down, I might be able to help you may some simple changes to your evening diet that can help pass the c-peptide test but I’d need to know more about you than you might feel comfortable sharing in a post.
