Originally Posted by
Roody
I understand that glycogen storage is initiated by high levels of insulin.
For glycogen synthesis storage you need to have decreased glycogen in storage. If you stores are full then no amount of insulin would make a difference, the excess would get stored as fat.
Originally Posted by
Roody
Type 2 diabetics and people with metabolic syndrome chronically have high levels of insulin, don't they?
Yes and no. Type 2 DM is extremely complex, so I will try my best.
In some cases there is a normal amount of insulin, but the pathway has many steps and an error in the steps can contribute to DM2. Some of the errors can occur in the cell, after insulin has bound with the receptor sight, some sort of post receptor error. There can be chronically high insulin levels for years before the disease manifests, DM usually takes a decade or two to manifest, but this is also not a rule. The excess insulin can cause cells to down-regulate insulin receptor sights to prevent hypoglycaemia, and thus can cause insulin resistance.
After a while beta cells may not respond as well to glucose and put out less insulin, so in this case there would be chronically low levels of insulin in the blood. There is usually a decline in the weight and amount of beta cells in DMs. The beta cells also co-secrete amylin with insulin, which inhibits glucagon secretion.
Other factors include leptin, adiponectin, and restin. These adipokines have been proposed to be associated with insulin resistance. I think that these hormones function somewhat differently when someone is obese, and that is why when someone loses weight there is less insulin resistance. Don’t take my word on this one, I am getting out of my league here.
It is thought that problems with insulin secretion can lead to resistance and vice versa.
Originally Posted by
Roody
How does exercise affect insulin levels, and how does this fit into the issue of glycogen storage and insulin resistance?
I am not sure but this is something that I curious about. I am going to be working with a DSN tomorrow so I think I will ask about this. I would think that one would have trouble storing glycogen if you could not get glucose into the cell I don’t see how glycogen could be produced.
Remember that even though quite a bit is known about DM2, in reality relatively little is known, it is an extremely complex and interesting disease.