Insulin Sensitivity vs Insulin Resistence

I have to get a C-peptide test done in order to get my insulin pump. I am almost positive that I still produce SOME insulin, and it is making me very nervous. My Endo says I am type 1... but I am just curious, because it will help put my mind at ease-

IF I am insulin sensitive (1 unit of insulin can drop my blood glucose 70-100mg/dl, and my IC ratio is 1u:30g... Then I couldn't possibly be producing too much insulin right? I would have to be producing very little insulin because otherwise I'd be type 2 and need more insulin to see the result I currently get?

Help? Reassurance? Any Type 2 using ONLY insulin and VERY small amounts? My TDD is less than 12u.

C-peptide isn't the definitive diagnosis of Type 1, antibodies are. But yes, in general, type 1's have lower c-peptides and type 2's have normal or even high ones. (They are producing lots of insulin but can 't use it well due to IR). But there are definitely ranges in how much insulin even type 1's produce. I believe somewhere there is a chart of average c-peptides for type 1's and type 2's. (Walsh?). But it doesn't necessary follow that if you are insulin sensitive you "can't possibly be producing too much insulin". You could be producing some (still within the type 1 parameters) and as you produce less your insulin use will go up a bit.

Have you had antibody testing?

My I:C ratio is really different from yours... 1:10 to 1:16 depending on the time of day. It seems to just vary from one individual to the next.. depending on a lot of factors.

My c-peptide was 1.1 (low end of normal) when tested, but it was also 2 hours after a meal.

I remember seeing a chart in Walsh's Using Insulin book for average TDD.. and I was at the lower end of the range they listed, so I'm sure you're far below even that. But I wouldn't hang my hat on that being the determining factor just yet..

I hope all goes well this week, I know this has been really long and drawn out for you! I will keep my fingers crossed. :)

A c-peptide is a marker for how much insulin you are producing. A meaningful c-peptide is performed when you have an elevated blood sugar (which would presumably drive an insulin response) and then you either have a low or high c-peptide measurement. This would indicate insulin deficiency or insulin overproduction respectively. The results of the c-peptide only indicate insulin resistance if you have a high reading. This is unlikely given your having already an observed insulin sensitivity.

I am a T2. I had the c-peptide, I think I measured 1.6 ng/mL on a reference scale of 1.4-3 ng/mL. My blood sugar at the time was 130 mg/dL. This basically indicates I am insulin deficient, but says nothing about my resistance. As it turns out, I am insulin resistant. My I:C is 1:4 to 1:10 and I use about 15 units a day just for my bolus. I use an ISF of 20 for corrrection, but I almost never correct. The charts in books like "Using Insulin" are guidelines. As a T2, over 200 lbs, my TDD is within the norms from the book. But if you eat low carb, you will often need more insulin.

Getting a proper diagnosis can be frustrating. I've never had much luck getting the right tests. Getting a c-peptide took 2 years of arguing. In your case, it is extremely unlikely that the results would lead to a change in diagnosis. If you were a T2, you would have observed insulin resistance and required more insulin independent of what state your beta cells are in.

So if I am reading your comment correctly, my ISF is 100 so I am very sensitive to insulin. That would mean my cpeptide should be relatively low?

Not necessarily--Your body may still be producing small amounts of insulin that are supplementing the insulin that you're injecting. Some of the new research says that even long time T1s are still producing beta cells and killing them off, so residual insulin production can continue for years. That's one reason the C-peptide isn't considered a definitive test for diagnosing T1.

At dx, when I was in the hospital, my C-peptide was at .3 (of course, I was on IV nuitrition because the DKA made me too sick to eat--my body was majorly stressed) but I recently had a new endo redo a bunch of bloodwork (she wanted to make sure I really was T1)--my new (fasting--go figure) C-peptide was 1.1 (the bottom of normal) but my GAD antibodies were through the roof. Hopefully, I won't have to go through that specific blooddraw again, but you never know . . .

Good luck getting your pump.

Apples and oranges, juliannaegrl; read my comment above and Teowyn's below!

Sadly ify c-peptide isn’t below normal then my insurance won’t cover the pump even though I am type 1.

I would fight that juliannergrl. The last c-peptide I had was when I lived in Guatemala and though it was below normal, nobody here in this country has tested it. All I needed for my pump approval was an A1C (and it was 6.5, and I didn't hear any of the "that's too good" stuff). So I think these things are individual. I would have your doctor write a note for your insurance as to why it would be good for you to have a pump. The "below normal c-peptide" requirement doesn't even make sense. In addition to being a Type 1 (I assume you got antibody testing which is the definitive diagnosis, not c-peptide) You are insulin sensitive and need low doses which means it's really hard for you to dose accurately with MDI.

Hi Juliannaergrl: No doubt you have Type 1 diabetes, but a bummer that you have to get a c-peptide to qualify for a pump. Maybe you can get an exception via your endo? Especially when a person is newly diagnosed, he/she will still have some insulin-producing remnant beta cells. An insulin pump and tight control can prolong the life of the beta cells, thus prolonging your "honeymoon." And prolonging the honeymoon has enormous benefits, such as greater blood sugar stability and lower risk of complications. All so worthwhile. Good luck!

Well, it is a bummer that anyone has to jump through hoops to get a pump, particularly if it helps them markedly improve control. Sadly, as a T2, the requirements are even more onerous, and I am unlikely to qualify for a pump anytime in the near future.

No, an ISF of 100 suggestst that you are insulin sensitivity, which means that it is very unlikely that you would produce "large" amounts of insulin and any c-peptide would also not show "large" results.

I believe 10% of T1 can be antibody negative.

Yes, some don’t have currently measured antibodies.

Hi bsc: It is a crazy world, indeed. But you have a relatively low c-peptide, I wonder if you could qualify on c-peptide alone? Just speculating. I really am sorry that "the system" is just so plain stupid.

My Endo said it could be upwards to 20% of people. She said some people only have antibodies at diagnosis and then don't have them after a period of time. And some people never test positive for them but still produce no insulin or very little insulin.

Because I was Dx Type 2 initially, and no antibody testing was done at that time it's not surprising that I only show trace antibodies 3 years later. She said bottom line, if you HAVE antibodies it is a definitive Type 1 Dx, but if you do NOT, it still doesn't rule it out.

Based on multiple factors- Weight, Insulin Sensitivity, Failure of various oral meds to positively effect my B/G, and then the trace amount of antibodies - that's how I got my Dx.

Also, SOME type 2's also test positive for GAD antibodies- It's rare but it DOES happen.

I have Aetna. Here is Aetna's current criteria (you qualify either under (A) or (B)):

A.Members must meet all of the following criteria:

1.The member 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
2.The member has completed a comprehensive diabetes education program; and
3.The member 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
4.The member meets at least one of the following criteria while on multiple daily injections (more than 3 injections per day) of insulin:

a.Dawn phenomenon with fasting blood sugars frequently exceeding 200 mg/dL; or
b.Elevated glycosylated hemoglobin level (HbA1c greater than 7.0%, where upper range of normal is less than 6.0%; for other HbA1c assays, 1% over upper range of normal); or
c.History of recurring hypoglycemia (less than 60 mg/dL); or
d.History of severe glycemic excursions; or
e.Wide fluctuations in blood glucose before mealtime (e.g., pre-prandial blood glucose levels commonly exceed 140 mg/dL); or

B. The member has been on a pump prior to enrollment in Aetna, and has documented frequency of glucose self-testing an average of at least 4 times per day during the month prior to Aetna enrollment.

Aetna has dropped the c-peptide qualification, but I would have to show poor blood sugar control in order to qualify. It is important to note that Aetna has modified their policy (as of 2/3/12) to "remove the requirement of beta cell autoantibody positivity or low fasting serum C-peptide level as a prerequisite for use of an insulin infusion pump." Medicare requires a c-peptide below 110% of the lower end of the reference interval, but not Aetna. All I have to do is demonstrate self-destructive behavior.

I'm glad I don't have Aetna. Why does the insurance industry insist on poor control to stipulate someone could qualify for a pump? When 1) You could make an argument in the other direction, that decent control is needed to demonstrate knowledge of management issues 2) Anyone can reduce their A1C and that's a good thing and 3) A1C is not the be all and end all and the pump enhances quality of life in oh so many ways.

I think I answered my own question: Because it's the insurance industry and their goal is to make (save) money, not help people.

Just to add my own info: The only thing I had to do to get my pump (Blue Cross/Blue Shield) is get an A1C and the results were 6.5

Ack, bsc! Like I said, just plain stupid. My endo had to work really hard to get the Dexcom for me, because my control is too good. I asked my endo why should I be penalized for excellent self-care? It's funny, I had a visual of you wearing an OmniPod.

My insurance is almost exactly the same except I have to have the c-peptide that says I am not making enough insulin i.e. not making TOO much. Hopefully I do not make too much, I'd be very surprised with the insulin sensitivity factor I have, coupled with all the running and working out, careful diet etc etc.