Association between Insulin and Body Fat

This report discusses the role of Insulin, c-peptide and leptin as markers in predicting the trends for Intra Abdominal Fat (IAF) and Subcutaneous Fat (SCFAT), and progression of Insulin Resistance snd Insulin Secretion
https://diabetes.diabetesjournals.org/content/54/4/985

Note that this report was published in 2005, which precedes the Newcastle Diet studies.

NicoleC1971 said:

Leptin has been known about as satiety hormone since the 90s and the paper notes an association which generated a hypothesis that others such as Taylor have gone on to prove via his RCT and use of advanced imaging. I am guessing he measured insulin and leptin as well as visceral fat?
I do not know how long it will take for insulin levels (and leptin too but mainly insulin) to be routinely tested to allow earlier interventions and prevention of metabolic disorders including diabetes. Any guesses?

Click to expand...

The study that Roy Taylor did on insulin secretion and beta cell output was not Counterpoint, but the Counterpoint study copies the findings but not the process behind them. The small study was only 11 participants, with 2 control persons. It was only the insulin clamp GTT and it only measured c-peptide. Table 2 of that study give the averaged results at different stages of the trial. I was not aware that Taylor measured Leptin in any of his studies.

If the study I linked here is valid, then the drop in c-peptide reported in Counterpoint is not due to the weight loss directly, but is reflecting a reduced demand for insulin. I think that makes sense.

My research into c=peptide has unearthed the following study
https://onlinelibrary.wiley.com/doi/10.1111/pedi.12609

It may explain why TOFI are more likely to be diagnosed T1D since low c-peptide tracks low BMI.

This effect does extend into T2D land too
https://pubmed.ncbi.nlm.nih.gov/15049937/

Neither of these studies appears to quantify the effect.

Studies of this nature seem to be primarily associated with T1D and hence are pediatric, so the China study above seems to be fairly unique in observing T2D adults.

But it seems there may be an effect on c-peptide due to body weight that may extend to adults. It may explain in part why the Newcastle Diet studies showed that insulin levels decreased during the trial. It may be a confounder to that study.

Here is another report that suggests a correlation between BMI and c-peptide levels. It was dismissed as being hyperinsulinemia probably due to gestational diabetes, rather than being a causal factor in itself, which figures. My question would be was it all the obese women scoring high, or just a few? It may explain why the OGTT is used to check gestational diabetes, and why it is not rolled out to the general public (until the c-pep test decison change last week)
https://core.ac.uk/download/pdf/268474379.pdf

Just a thought.. If c-peptide is correlated to BMI then will this affect a HOMA-IR or HOMA-B test?

The answer seems to be a resounding YES
https://pubmed.ncbi.nlm.nih.gov/20655552/

So, if you use these tests for checking whether your diabetes control regime is improving your insulin responses, or IR then make sure your BMI does not change between tests.