C-Peptide Tests 2005 & 2007

Since my C-Peptide levels are so low, how come my blood sugar levels are normal?  Without medications or injected insulin?  There are some good medical experts that are stumped by this.  So . . . What’s your guess?

C-Peptide is a fairly common test for your pancreatic function because it tracks fairly closely with you body’s own ability to produce insulin, largely because, even if you’re injecting insulin, C-Peptide can give a rough idea of how much internal insulin you’re body’s producing.  It’s also a popular test because C-Peptide hangs around in the body longer than insulin does, so many doctors say C-Peptide is a more reliable measure of your body’s insulin function because it doesn’t rise and fall as much.  Some cynics say that you have to use a very good lab if you don’t want a sloppy insulin measurement, and so most doctors don’t bother to do it.  That’s what cynics say.  As you can imagine, there’s plenty of debate about the merits of testing C-Peptide versus insulin, and plenty of very fine doctors and researchers  prefer to measure one versus the other.

As for what C-Peptide is, it’s a little protein that the body  uses to “packages” insulin.  While the C-Peptide and insulin are joined together, the molecule is called “proinsulin.”  When your body releases insulin, it sort of pulls off the c-peptide wrapper, and voila!  There’s the insulin, fresh and ready to start giving instructions about whether cells should take in stuff like Vitamin C and sugar, and whether it’s time for cells to move from maintenance and repair to lots of cellular division.

Once C-Peptide’s “unwrapped” to free up the insulin, it’s not just an empty baggy that the body throws away.  Instead, C-Peptide may do some mopping up jobs, reducing inflammation in interesting body parts such as your blood vessel linings.  When diabetics inject insulin, they get that insulin without any C-Peptides attached.  That’s why checking a diabetic for C-Peptides is a way to gauge how much insulin their body produces.  As another bit of trivia, there’s some thought that diabetics SHOULD inject some C-Peptide, or use it in some way, to reduce inflammation.

Since 2005, I’ve had 2 tests for C-Peptides.  These were the results with a little side information to put those results in context.

These C-Peptide tests were done at different labs, which use different ranges for what counts as “Normal.”  In both cases, my C-Peptides were low, either at the bottom of normal or below it.  At some labs, when they give a result at the bottom of normal, it basically means it was AT LEAST that low and might have been lower.  I don’t know if that was the case for me, but even in the second test, it was low enough to be at the bottom of their normal measurements.

I’m including my fasting blood sugars and Hemoglobin A1Cs to give a context for those low C-Peptide numbers.  Fasting blood sugar means a blood sample taken after you haven’t eaten for at least 12 hours.  Below 110 is considered normal, and 126, I think, is the number these days that’s considered “official diabetic.”  Perhaps a better number to track, though, is Hemoglobin A1C.  It’s a rough measure of the average amount of sugar that’s gotten gummed up your red blood cells during the typical life of a red blood cell, which is roughly three months.  Notice the word, “rough.”  That’s because, if your blood cells are especially prone to having sugars attach to them, the HA1c can be higher than any blood finger pokes indicate.  Or, if your red blood cells tend to hang out and survive for more than three months, then they can end up with more sugars attached to them even though your blood sugars are actually lower.  Stuff like that can affect your HA1C.  Which makes it rough.  Yet, despite those fudge factors (ah, me, given the point of this blog, we probably shouldn’t use words like fudge.  And I can’t think of any other phrase that would be more fatrocentric.

Anyway, despite the fact that the HA1c is imprecise, it’s a better measure for your blood “sugars” than a fasting sample, because fasting blood sugars can jump up and down a lot.  In fact, if you really want to impress a doctor, and keep him or her from pointing their finger at you and going tsk, tisk, you can push down a typically high fasting sugar by starving for a few days, or if you’re a diabetic, injecting a whopping dose of insulin.  Nasty, and in fact, it can be very dangerous.  In contrast, it’s not as easy to lie about your A1Cs, because they are an average of a whole month.  A “normal” A1C is below 6.0.  That’s even though the American Diabetic Association is now shrugging its collective institutional shoulders and saying that 7.0 is probably good enough.  The ADA is saying this because there are plenty of tests now which report that if you try to force the A1C down below 7.0 by upping your dosage of medications, it increases your risk of keeling over from a heart attack.  Well, this does NOT ‘t mean an A1C of 7.0 is healthy.  Above 6.0, experts on the tiny blood vessels in a person’s eyes warn that elevated sugar levels are already damaging the eyes tiny vessels.  That can lead to blindness.  There are similar tiny vessels in your kidneys, and if they get damaged, that can lead to kidney disease.  There are similar tiny vessels in a man’s penis, and when they’re damaged, that can lead to erectile dysfunction . . . which is why erectile dysfunction is also considered a warning sign that someone’s at risk for heart disease.  Taking Viagra might bring life back to the penis or the vagina, but it doesn’t reduce the heart disease risk.  In fact, it may INCREASE the risk.

By the way, unlike enlivening erections through meds, or reducing HA1cs through medication, using diet, exercise and stress reduction to lower HA1cs doesn’t seem to carry a heart attack risk.  Instead, these options seem to enhance heart attack prevention. And damage to the microvascular system of tiny blood vessels in the eyes, the kidneys, the penis, the vagina, and so on can sometimes be reversed once HA1c goes down to normal.

Which is why I kind of try hard to keep an eye on my HA1cs, and get a little nervous any time they’re taken.  What are they going to tell me this time?  I always worry.  So far, knock on wood, they’ve been in the normal range.

Which gets me back to my C-Peptide tests.  You see, all these normal blood sugars and HA1cs have happened with me NOT taking insulin or medications.  That’s worth pointing out because there are thousands, perhaps millions, of diabetics with higher fasting blood sugars and HA1cs, who have been told by their doctors that a low C-Peptide level is PROOF that they need to be using medications to keep their blood sugars and HA1cs closer to the normal range.  There are thousands, perhaps millions, of diabetics, with C-Peptide levels HIGHER than mine, who are also told by their doctors that they need insulin and/or medications.  And there are also huge numbers of diabetics who have been given insulin and/or medications without ever having their C-Peptide levels or their own insulin levels checked.

For those on medications who know their C-Peptide levels, I’m curious what their C-Peptide levels are, and what their HA1Cs are, and what their medications are.  If they’re on medications or injecting insulin, and their C-Peptide levels are the same or higher than mine . . . I’m curious.  Since my C-Peptide levels are so low, how come my blood sugar levels are normal?  Without medications or injected insulin?  There are some good medical experts that are stumped by this.  So . . . What’s your guess?