Dr. Jason Fung

So, you know, if you're not measuring your insulin levels, you've missed that whole entire sort of early part where your blood sugar, your A1C is normal, but your insulin levels are going up.

So I actually measure the C-peptide, which is not a perfect marker.

It's a measure of insulin.

So fasting insulin is a very variable measure, right?

So fasting insulin is going to go boop, boop.

It's going to go up and down so much that you really can't make heads or tails of it.

C-peptide's a little less variable.

And you can also do a fasting C-peptide.

And that's going to give you an idea of how high your insulin levels are.

So I've seen so many people who have fasting C peptides or random C peptides that are four or five times normal and low normal sugars, like A1Cs of 5.5%.

So it was all that insulin that's keeping the sugar low.

That's not a normal situation, right?

Your insulin levels need to be low and your blood sugar level need to be low in order for you to be off of that spectrum of sort of normal weight to obesity, to prediabetes, to diabetes.

Because that's where that

insulin level goes up.

I say C-peptide, fasting C-peptide, random C-peptide is a good marker, but you actually have to follow it over time because it's quite variable.

So because I follow patients over many, many years, I actually measure them

routinely, I see where people are high and then I talk to them and I say, hey, look, let's adjust your diet a little bit because it's about the diet, right?

Because insulin levels are related very much to the diet.

And you can see them come down and you can see them go up, right?