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Should I Keep taking Metformin?

My gp told me when I asked that though metformin at high dosage is contraindicated i with CKD that low dosage was permissable so even though I have impaired kidney function he would prescribe metformin at the lowest dose of 500 mg per day.
 
From my knowledge and clinical experience this is another difficult question to answer categorically.
I would make a few comments. Metformin used in prediabetes has been shown to prevent/delay the onset of full blown T2D. In the biggest UK study UKPDS it came out well on top of other treatments in terms of outcomes. It tends to make your insulin levels lower and personally I think in pre diabetes or early T2D or having reversed T2D you want to have well controlled BG levels and low insulin. So for all these reasons I would keep on with it PROVIDING you are not getting side effects. Someone posted about big pharma. Metformin is off patent ie generic companies can make it and it’s not expensive so there isn’t the mega bucks in it that big pharma want. It is almost always the first glucose controlling medication prescribed by doctors because it has good evidence it works and doesn’t raise insulin. At the end of the day your control seems excellent. If you stop it and get your HbA1c repeated in 3 months - assuming all else is roughly the same - you’ll get a good idea how much it is helping.
 
Metformin does need to be used with caution in CKD. CKD has 5 stages and you need to know what stage you are at. Your GP can tell you this from a routine blood test that measure EGFR - how well your kidneys are filtering your blood. Also you need to know if this EGFR is stable or deteriorating. Many people with T2D have ckd3 and if the condition is stable may well be ok to stay on metformin or a reduced dose of it while having ckd monitored by EGFR. Best to discuss your concerns with your nurse or doctor and know what your readings are and if they are stable. If your ckd is more severe most doctors would advise stopping the metformin and using other meds’ to control BG.
 
Thank you for your input. I take 1000g Metformin per day and restrict my carbohydrate intake. My HbA1c has been in the non-diabetic range for the last 4 years. However, over the last year my blood creatinine levels have increased. Allowing for age adjustment, the results are at the top end of normal (94 micromoles/l?) and I am becoming concerned. The inputs from both you and Brunneria have made for interesting reading.
 
From the NICE guidelines:

"
in adults with type 2 diabetes, review the dose of metformin if the estimated glomerular filtration rate (eGFR) is below 45 ml/minute/1.73m2:
Stop metformin if the eGFR is below 30 ml/minute/1.73m2
Prescribe metformin with caution for those at risk of a sudden deterioration in kidney function and those at risk of eGFR falling below 45ml/minute/1.73m2"

http://www.gpnotebook.co.uk/simplepage.cfm?ID=x20080603110134225450

My eGFR over the last year or so has been steadily dropping and is now at 50 so at the moment according to NICE I am alright to take metformin at a low dose but if eGFR falls much lower I will stop taking it.
 
Generally speaking EGFR is a better measure of kidney function and would be preferred over creatinine levels. Remember also that conditions other than T2D can cause kidney function to deteriorate. You should be monitored for microalbuminuria which is an early warning sign of diabetic kidney disease. Best to raise your concerns with your hcp.
 
I should have also said other medication particularly ACE Inhibitors can be related to this problem but they are also protective of the kidneys - quite hard to explain in a short post but again best to speak to your hcp
 
I’m not totally clear what your readings are. There should only be 1 result per date. The reference ranges can vary for different populations. The readings above are all well within normal. You have to remember lab tests are only accurate to +/- around 5-10% so 2 tests on consecutive days can vary quite a bit and doesn’t mean anything clinically. You are definitely safe to continue metformin with the results posted here - from the EGFR perspective.
 
You need a series of 3 or better 4 or better 5 EGFR results to establish a definite trend in what is happening. Simple things like being a bit dehydrated when you have a test can affect the individual test.
 
The issue with mild kidney disease and metformin is that:
  • Metformin reduces the likelihood of kidney disease getting worse due to Type2.
  • But kidney disease increases the very low risk of taking metformin (Lactic acidosis) by a little bit.
  • Often doubling the dose of Metformin has very little additional benefit.
Many more people die from kidney disease than the side effects of metformin (Lactic Acidosis)...... It has not even been proved that metformin increases the risk of lactic acidosis. But if the kidneys are about to give out, recusing the work the kidneys have to do, by avoiding most drugs makes total sense.

Hence it is a balancing act with no absolute rules.
 
I agree totally. When I started med school my pharmacology prof said “all medicines are potentially poisons and should be looked upon that way”. Everything is a balance of pros and cons. On balance metformin is likely to offer many more benefits than dangers unless you have progressive CKD and EGFRs that are below 50 and deteriorating. That said the forum is not here to give specific advice as other meds’/conditions ie the whole person needs taken into account. Discuss it more with your hcp.
 
Thank you
 
Metformin is not glucose controlling.
I am not sure how it is supposed to help - but lowering blood glucose is not one of its properties. It does interfere with the ability of the liver to release glucose, but I am not sure how that helps in the long term.
 
Metformin lowers HbA1c. It helps reverse insulin resistance meaning glucose can enter the tissues more easily and as you say it reduces hepatic glucose output. It lowers insulin levels and does not cause hypos. In early T2D or prediabetes you want to aim for low insulin and good BG control.
 
Marginally at best in my experience. But I hate meds ... any
 
Sure. Lowering carbs, lowering calories, losing fat mass/weight and taking more exercise - walking etc will probably work better.
 
Metformin improves Insulin Resistance

T2D is often a disease of Insulin Resistance

So of course there is no good reason to take it, because it is much more important to be able to say “no meds”

Means you can feel far superior to the poor saps who take them.....
 
Isn't it strange the plant metformin is derived from Goat's rue, French lilac, Italian fitch, and professor weed a few of it's many names has been used to treat diabetes since the middle ages if not longer yet we tend to think of it as something novel and new and unnatural not something that has stood the test of time.
 
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