Tuesday, May 9, 2017

C-peptide...Part 1

C-peptide....Part 1
C-peptide was discovered in 1967. The first actual use of a C-peptide test was in 1972. In more recent times, C-peptide has been found to have an effect on microvascular blood flow and tissue health. Microvascular complications pertain to the smaller blood vessels and include retinopathy, neuropathy and kidney failure.Type I diabetics typically have very low levels of C-peptide because most of their beta cells have been destroyed. This has been seen in the development of long-term complications
I used animal insulin for 50 years, and it contained C-peptide, which helps protect us from many diabetes related complications. That may help explain why I, and so many other long term type 1 diabetics, did not have those complications back then. In the 1990s I started using synthetic insulins, which did not contain C-peptide. By the end of that decade I started having some complications. Was that a coincidence? I don't think so.
 I was diagnosed with spots of retinopathy in both eyes, and neuropathy in my feet. I started using a pump and my control was more stable. The retinopathy disappeared, and has not returned, but the peripheral neuropathy is now in my feet, legs, hands and arms. There is not enough pain to require medication at this stage. I also have autonomic neuropathy in the trunk of my body. None of my neuropathy is severe, but it is very annoying.
C-peptide has been shown to significantly improve nerve and kidney function. It has also been reported to have anti-inflammatory effects as well as aid repair of smooth muscle cells.
"Newly diagnosed diabetes patients often get their C-peptide levels measured as a means of distinguishing between type 1 diabetes, Maturity Onset Diabetes of the Young (MODY), Latent Autoimmune Diabetes of Adults (LADA) and type 2 diabetes.
The pancreas of a type 1 diabetic does not usually produce adequate insulin, so a decreased level of C-peptide is expected. Some secretion can still be present during the honeymoon stage for type 1 diabetics. C-peptide levels in type 2 diabetics are normal, or even higher than normal. Determining the amount of C-peptide in people who inject or pump synthetic insulin can help to determine how much of their own natural insulin these patients are still producing, or if they produce any at all.
The results of a C-peptide test can vary from lab to lab. So different labs may have different 'normal' ranges. Doctors will sometimes evaluate your results based on your health and other factors. A C-peptide value that falls outside the normal range may still be normal for you. The C-peptide and blood glucose levels are measured at the same time to give a better evaluation.
A normal C-peptide level may be indicated as – Fasting: 0.51-2.72 nanograms per milliliter (ng/mL) or 0.17-0.90 nanomoles per liter (nmol/L)"
In the early stages of the Joslin Medalist Study 725+ participants were tested for their C-peptide levels. That test along with a glucose tolerance test showed that more than 66% of these long term diabetics were still producing some of their own insulin. My C-peptide level was less than 0.1, showing that my good health after 71 years of diabetes has to be explained by factors other than insulin secretion.
"Persons with LADA typically have low, although sometimes moderate levels of C-peptide, as the disease progresses and high blood glucose levels appear.
The most common MODY syndrome may also have normal fasting C-peptide results because the flaw in this case is in the secretion of insulin in response to rising glucose and fasting secretion is still near normal. Their postprandial C-peptide however is below normal with elevated blood glucose."
I have believed for many years that C-peptide present in the animal insulins I used for 50 years may have protected me against certain complications. It may help explain the longevity and good health of so many of the Joslin Medalists. Today's synthetic insulins do not contain any C-peptide. I asked Dr. King, head of the Joslin Medalist Study, about this. He said he does not think that C-peptide is a factor in explaining the longevity and good health of so many of the medalists. Maybe he will have changed his mind when the study concludes.
The links below are my references. They discuss C-peptide in much more detail.
Note: In a few more days I will post Part 2 of this discussion: An online discussion in the Diabetes Daily group; An attempt to produce an injectable form of C-peptide; Adding C-peptide to synthetic insulin.

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