Metformin - how does it work exactly

[The Governor]

Well, I'm a week in, still getting used to the various foods I can't eat and the seemingly few that I can.

I'm now on 2 Metformin a day, after meals, building up to 3 next week.

However, I'm not entirely sure the Metformin is doing much. I seem to get the best results from exercise.

For example, I had my carb counted tea tonight (scampi in breadcrumbs, green beans and cabbage) I went up to 9.1 after an hour, even though I take a Metformin with my meal.

Knowing I was high I went on the exercise bike to bring me down.

My point is, if the Metformin works, why do I shoot to 9.1 after an hour? Is there some sort of cumulative effect so you don't get the full benefit until you're on 3 a day?

 

[martinbuchan]

9.1 after 1 hout is not that bad. <10 is within normal range, but few non diabetics will reach that high with that meal. I find breadcrumbs send me quite high. Many aim for <8 1 hour post prandial and <6.5 2 hours post prandial. For me it is how I judge the accuracy of my insulin dosing related to the activity of the meal.

Once you are on maximum dose you might see a big change.

 

[Nellie]

According to my Gretchen Becker supplemented by a quick google.

Firstly theres no complete understanding of how metformin works.

First a quick diabetes lesson. Sorry if I'm going in to detail you know/too much detail :wink: If you want to skip the detail the summary is at the bottom.

Muscles need insulin to work effectively. Insulin acts as a key allowing the glucose to enter the muscles. Many people with type 2 have a fault in that insulin doesn't do this job effectively so glucose builds up in the blood.(insulin resistance) When exercising, muscles need much less insulin in order to access glucose.

In people without diabetes a second hormone glucagon 'senses' when the blood glucose is low and signals to the liver to produce/release more insulin. People with type 2 may have much more glucogan than normal making the liver produce/release more glucose even though there is plenty in the bloodstream.

The liver forms glucose from non carbohydrate sources (amino acids and fats). This is called hepatic gluconeogenesis A person with type 2 diabetes may have three times the normal rate of gluconeogenesis.

I)It is thought that metformins main action is in reducing the hepatic gluconeogenesis . That is the formation of glucose from the liver.
2)It may help reduce the absorbtion of glucose in the digestive system.
3) It may help the cells take up glucose in order to work (in other words it may help overcome insulin resistance.)
4) It is very good as an apetite supressant so helps people who need to lose weight. Its sometimes prescribed for this for people without diabetes.


So to conclude it seems that its main action stops your liver from producing extra glucose. At the same time It may reduce the amount that is absorbed from your meal and may help your cells to utilise it.

Thats why you are finding exercise so effective. The metformin is stopping your liver from producing extra, uneeded glucose. Because muscle cells need very much less insulin to to use glucose during exercise, the glucose is being used rather than staying in the blood stream. Another good thing is that the reduced insulin resistance during exercise may last for some time after the exercise stops. (and it may help weight loss which in turn reduces insulin resistance)

Here endeth the lessson for today!

 

[The Governor]

Martin - thanks for the reassurance, any news is good news for me at the moment!

Nellie - Once again I'm grateful for an old hand taking the time out to explain some basics to an annoying naive noob That was really useful.

My GP has given it to me on the understanding it will help "bind" insulin to my blood (your point 3).

Your other points are useful though, although I'm slightly disconcerted that nobody really knows what it's doing! :shock:

So if I understand correctly, it may be reducing the glucose produced by my liver, which might explain why it isn't having an effect on my rise after meals? I was labouring under the misapprehension that each tablet was reducing the glucose absorbed from the meal I'd just had, but your explanation makes some sense of what I'd seen so far.

It also goes some way to explain why at the moment I'm so high (compared to what a normal person should be). Like I say, I thought it was tackling my food intake, rather than generally lowering my glucose levels, so presumably as my dose goes up my levels might become more stable...?

Of course, you'll now tell me I've totally misunderstood and I'll kill myself

 

[timo2]

Hello gov,
The link below is not about metformin itself, but it does explain the functions that
metformin aids/suppresses and how the are interlinked.
The hormones discussed have a direct connection with the hepatic gluconeogenesis
that Nellie mentioned earlier.

OH NO!, HERE COMES THE SCIENCE LESSON!

Warning: The above link may turn you into some kind of "expert".

Regards,
timo.

 

[The Governor]

Cheers Tim, I had to laugh at the flow chart at the end of the text. To summarise.

Diabetes > High Blood Sugar > Dead

Very uplifting

 

[timo2]

Hey Governor,
If it makes you feel any better - none of us are getting out of this one alive.

Ahh...that's cheered me up no end.

 

[The Governor]

lol, I'm not sure if it's a good sign or not that the gallows humour has set in for me already

 

[a_hilton]

From what I understand, metformin works via several mechanisms.

In the short term, metf slows the rate of absorbtion of glucose from meals within the stomach and the small intestine. This has the effect of lowering the Glycemic Index/Glycemic load of the meal, reducing the insulin response.

In the short/medium term, metf reduces the livers tendancy to uptake blood glucose and convert it to glycogen. The liver does this because it is 'insulin independant', i.e. it does not need insulin to remove glycogen from blood. This effect might cause your high post prandial BG levels. After all, if the liver isn't uptaking as much glucose, then it will still be hanging about in your blood.

In the long term, metf increases the number of GLUT4 glucose transport units in skeletal muscle, improving glucose tolerance/insulin resistance.

Alex