Can someone help me understand the c peptide test? I found out the result of mine was 4.5. What does that mean? I was diagnosed type 1 in December in DKA and a BG of 550. This is the first time I've had bloodwork done since diagnoses (test was done exactly 2 months after diagnosis). Right now I'm honeymooning, so I'm still making some of my own insulin but I'm using lantus as well. BG are good fasting and before meals 80s & 90s. 2 hour post meals are high 100's to 220ish. My endo thinks i'm definetly going to add some novolog to the mix as well.
But anyway, I'm really confused as to what the c peptide test measures. What are the ranges for guidelines and things like that? What do the results mean?
I had the test done fasting (8:00 am) if that helps anything
By the way in only 2 months after diagnosis I dropped my a1c from 14.8 to 7.6! So that is definetly some inspiring news!
Yes, this means that you are still honeymooning! Your natural insulin production will likely decrease over time (though it’s hard to predict at what rate). Just don’t be surprised if you start needing significantly more insulin than you do now. My amount of injected insulin doubled when my honeymoon was over. As I remember, my honeymoon ended quite suddenly and one day I woke up with a blood sugar over 400 and new it was time to increase the insulin doses.
Congrats on the A1c!! Does your doctor want you to add Novolog for high carb meals? It might not be a bad idea to prevent you from going high after meals. You should definitely not go above 180 after meals, though even better if you can avoid going over 140 (I won’t tell you to do that because I am still not able to – though that’s my goal!!). A small dose of Novolog only with high carb meals might improve your blood sugars a lot!
There are two measurement units for c-peptide, ng/mL and nmol/L. Since you are in the US, you probably were given a c-peptide in the ng/mL units. Different labs will quote different normal ranges, Labcorp quotes me 1.1-4.4 ng/mL as the reference range. Interpreting the c-peptide really depends on your blood sugar at the time of a test. If you had even a mildly elevated sugar and without any other knowledge, you would probably be diagnosed as a type 2. In either case, the result of the test shows that you still have some significant insulin production. That is a good thing. If you tested with a low c-peptide with a markedly elevated blood sugar, then you would be considered insulin deficient.
Does having external insulin in the body effect the results? I mean, if I took my normal dose of lantus the night before, would that skew the findings of the test?
There seems to be contradictory information. Type 1 diabetics cannot produce insulin at all and therefore little or no C-peptide which is related to insulin production. C-peptide values for type 1 diabetics are generally very low, way under 5. C-peptide values around 5 and up are typical of type 2 diabetes. That’s why I spoke of contradictory information.
That’s what I thought. But I really don’t present as a type 2. I’m not overweight, there’s no family histroy, i went into the hospital in DKA witha fasting bg of 550 blah blah blah. My endo when she brought up c peptide said okay you’re definetly type 1. The only thing I’m thinking is that maybe she said .45 not 4.5.
There’s a world of difference between .45 and 4.5. However I am not a doctor so take what I say with lots of salt. (Big Grin). OTOH, you don’t need to be overweight to be type 2. The story is told by your body chemistry which I am sure your endo has monitored carefully to make her diagnosis. One of the weirdest aspects of diabetes is just how each individual case can vary. Everybody seems to have a different mix of symptoms, reactions to medicines, ancillary health issues, etc. So don’t go looking for some group to join because your all the same. You need to concentrate on your specific needs and learn how your body works.
Given that Tim was diagnosed only a few months ago and currently only requires minimal injected insulin, it is possible that his body is still producing a significant amount of insulin, but you are right that this will decrease over time.
Tim – do you know what your blood sugar was at the time? If your blood sugar was even slightly elevated, then your body would be producing as much insulin as it can to bring it down. Your natural insulin production is stimulated by rising blood sugars.
The test you need to have is for antibodies.I have been blogging about people who where initially diagnosed as type 1 but after the DKA was fixed, they were found to be type 2. They were found to have no antibodies and a c-peptide test>.9. The c-pep doubled after six months.
What type of carbs are you taking in. High carbs tend to give high post prandial numbers.
Unfortunately, with a blood sugar of 110, the c-peptide probably does not tell you anything. In my case, my c-peptide was measured as 1.8 ng/mL with a blood sugar of 133 mg/dl. My endo told me that even with those values it did not show any insulin deficiency. If your blood sugar is nearly normal, your body is not asking your pancreas to produce much insulin, so it does not produce much. If you had a markedly elevated blood sugar, your body would have been screaming “MORE INSULIN” and a failure to produce the needed insulin would have clearly showed insulin deficiency.
So, the good news is (if your numbers are accurate), you are not displaying a serious insulin deficiency and you should be enjoying a wonderful honeymoon.
Carrie’s pump trainer is correct. Exogenous insulin dosed does not correspond to any C-Peptide because it is made in a lab and there is no connecting peptide to proinsulin in vials of insulin purchased from a pharmacy because it is 100% synthetic, which means using insulin will have absolutely no impact on your C-Peptide results. The test measures endogenous insulin production only.
But Scott, he has reported that he is producing c-peptide at the upper end of the reference range. He is in that honeymoon stage. So in Tim’s case, he actually might have even higher insulin production capability than shown in his test.
The reference ranges vary from one lab to the next, but if one uses Medicare’s criteria for coverage of an insulin pump, the amount should be a fasting C-peptide level that is less than or equal to 110 percent of the lower limit of normal of the laboratory’s measurement method. He reported the lab result, but unless I’m mistaken, the lab’s range was not provided.
Yes, but Tim indicated his c-peptide was 4.5 ng/mL far above that the lower limit of basically all the labs. I think we are confused about what we are talking about.
You really need to know if it is .45 or 4.5 As other’s have stated that is a big difference. My only issue is lack of insulin for meals. My c-peptide was 1.7 with a fasting of 87 (these values are VERY close to what a normal person would have from what I understand) I am insulin sensitive but not a traditional T1 or T2. I lack antibodies but I do have the genetics for both T1 and T2.
Ok…with this said…if you are 4.5 and 110 for a FBS that is on the high side and it would be good if you had your antibodies checked. Regardless if you are happy with your care then…it might be a whatever.
But on the flip side… if you are at 4.5 there might be things you can do to make your situation better and stay where you are at for a very long time.
