Diabetes India
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metformin and B12

Each and every diabetic is prescribed with Metformin to control blood sugar.

It is also said metformin is safest anti diabetic drug.

It is also said B12 level is affected by metformin.

The exact action of metformin is not known

However metformin acts on Liver and we can see that effect in reduction of FBS.

It is also said B12 is stored in liver.(about 5 gms ??) and supplied to body in time of shortage.

is it that metformin acts by blocking some liver functions??? or it acts of circulation/recycling of B 12 and similar to B 12 what else is affected???

More studied members like @anup Concerned arunkumar Shashikantiyengar shrisamarth suramo Hidden Ashka9 and ofcoz my dearest friend MikePollard may like to discuss this for benefit of other members plz.

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Metformin reduces triglycerides, glucose, insulin, and hemoglobin A1C (a marker of long term glucose control). These blood markers are all proven heart attack risk factors. Yet not all studies show metformin reduces heart attack incidence.

One study found that when metformin was added to a group of non-overweight patients taking sulfonylurea drugs, there was a significant increase in overall mortality.71 This suggests that metformin should not be combined with sulfonylureas.

Furthermore, not all studies show that metformin reduces cardiovascular risk or improves overall survival in type II diabetic patients. There are several reasons to explain these discrepancies.

Metformin is known to cause vitamin B12 deficiency which translates into higher levels of artery-clogging homocysteine. The tiny amount of vitamin B12 and other B-vitamins found in commercial supplements is not always sufficient to offset this problem. Those who take metformin should ensure they are taking higher doses of B-vitamins (at least 300 mcg of vitamin B12) and check their homocysteine levels to make sure it stays in the safer ranges. One study showed that the addition of 5,000 mcg of folic acid to patients taking metformin reduced their homocysteine from 15.1 µmol/L to 12.1 µmol/L.76 Optimal homocysteine levels are probably under 8 µmol/L, but any reduction is helpful. Sadly, most diabetics prescribedmetformin don't check their homocysteine levels and don't take enough B-vitamins to prevent a deficiency.

Some studies show that metformin reduces free testosterone and total testosterone levels in men. Testosterone is especially important in male diabetics as it significantly enhances insulin sensitivity. Life Extension has previously published clinical data showing the critical importance of diabetic men to maintain youthful testosterone levels in order to improve glucose utilization.

The greatest challenge in evaluating clinical data on metformin is that it is often prescribed to debilitated patients who have undergone severe arterial attack for many decades. These diabetic patients are at significant risk of cardiovascular disease from a number of underlying causes. They need to take aggressive steps to correct all independent risk factors for vascular disease, something that is never done in clinical studies.

How Metformin Functions

Metformin reduces blood glucose levels primarily by suppressing glucose formation in the liver (hepatic gluconeogenesis).

More importantly, it activates an enzyme called AMPK (AMP-activated protein kinase) that plays an important role in insulin signaling, systemic energy balance, and the metabolism of glucose and fats.

Activation of AMPK is one mechanism that may explain why diabetics prescribed metformin have sharply lower cancer rates. For instance, in a controlled study at MD Anderson Cancer Center, the risk of pancreatic cancer was 62% lower in diabetics who had taken metformin compared to those who had never taken it.61 Diabetics suffer sharply higher incidences of pancreatic cancer than non-diabetics.

One of the metabolic imbalances of type II diabetes is the excess formation of glucose in the liver. To ensure that blood glucose never drops too low, the liver manufactures glucose in a process called gluconeogenesis. In type II diabetes, despite an elevated blood glucose level, the liver inappropriately continues to pump out glucose. This inappropriate outburst of glucose from the liver in type II diabetes patients is a classic hallmark of the disease. In fact, scientific data that measures glucose output by the liver shows that the typical type II diabetic produces three times more glucose in their liver than non-diabetics. And, as previously reported in this publication, even most non-diabetics produce too much glucose in their liver as they age.

Scientific data shows that metformin reduces glucose production and the rate of gluconeogenesis by anywhere from 24% to 36%, respectively, thus reducing blood glucose levels while lowering the amount of insulin that is chronically secreted. Metformin also enhances insulin sensitivity, thus enabling cells to remove more glucose from the bloodstream, which further lowers glucose and insulin levels. In a recent study conducted by a team of researchers in Italy, 500 mg three times a day of metformin reduced insulin levels by 25%.



I am 79 , a known case of Diabetes & BP , both under control with Medication ie 1tab of GLYCOMET 500SR &AMRYL 1mg in the morning. The HbA1C readings range from 5.8-6.2

For some time specially in winter I was facing problem of Breathlessness & during Cardiac Check up , changes were noticed in 2nd stage of TMT . I undertook Angiography from wrist ( Catheter ) when it was revealed that I hv .Blockages to the extent of 95% ,90% & 85 % pl. But instead of CABG I took 35 sittings of EECP & 20infusions of EDTA , Zero Oil Cooking & regular walking since March 2016 & am not having breathlessness problem now .

After reading adverse affects of Metformin on Liver functioning I am a bit concerned & seek your learned views recommendations pl.

Below I give my latest results pl.



IQR /MED 14%



AST /ALT -0.87

GGT 18






vIT b-12 ON 24.4.15 392, 25OH VITAMIN D 23.12 , FOLIC ACID ON 29.9.12-4.8, TESTOSTERONE ON 24.4.15-349.1

With best Wishes



AFAIK, it is the absorption in small intestine which is affected by metformin not liver storage.


so metformin also affects absorption from small intestine??


Without affecting absorption of glucose from intestine from food, how will Metformin act to reduce blood glucose level?


well.....does metformin affects absorption of glucose from Intestine???


Metformin functions to reduce absorption of ingested carbohydrates ( reduce absorption of carbs means reduces glucose absorption from food), suppress appetite, enhance insulin sensitivity, and most uniquely, metformin inhibits the release of stored liver glucose (glycogen) back into the blood.

One of the problems that frustrates so many people who follow a low-calorie diet, yet have persistently elevated glucose levels, is that the liver improperly dumps too much glucose into the blood. This of course is a vital life function in a starvation state, but for aging individuals, excess hepatic release of glycogen (called gluconeogenesis) causes them to suffer chronically high glucose and insulin levels. Metformin inhibits gluconeogenesis.

Drugs like metformin may be considered for its multiple benefits that extend beyond mere glucose control.

One side effect of metformin is that it can cause homocysteine levels to elevate ( because it reduces absorption of Vit. B12 which affect homocysteine levels too) This is less likely to happen to diabetics who already take nutrients that suppress homocysteine.( folic acid 5000 mcg daily reduces homocysteine levels) Those with impaired kidney function or congestive heart failure may not be able to take metformin.

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excess hepatic release of glycogen (called gluconeogenesis)

Glycogenolysis ?

Gluconeogenesis is synthesis of glucose from non-carbohydrate sources


Yeah, true...it should be "Glycogenolysis" and not gluconeogenesis......actually it is a mistake from site where I copied and pasted.

The below is the link to the post by Suramo....good article indeed.



Good post!Thanks for posting!!Waiting for more replies!!!

1 like

I have heard that metformin sometimes increases creatinine level in blood.I am taking metformin and had blood test for HBa1c test and creatinine test last month.HbA1C was 6.3 and serum creatinine was 1.8 and after 15 days without any medicine it was 1.70.I have no urinary problem and no burning sensation and normal .I consulted my diabetologist last week he advised me to stop metformin for 1 month and gave nephrozon and other diabetic medicine.He informed me that metformin sometime increases creatinine level.I also googled (does metformin increases creatinine?) and somewhere o a health board a diabetic-2 patient wrote that his creatinine level was increased and on doctor's advise he stopped metformin for 9 days and after 9 days his creatinine level was normalized.

Has any one experienced same problem?


rshrikant786 there are many learned members hereConcerned @anup Shashikantiyengar shrisamarth

Hop they will answer


Metformin does not affect creatinine but metformin clearance will be affected, depending on stage of renal function.

It is said that, if metformin is not cleared properly with impaired kidney function then there is chance of rare condition of lactic acidosis. But there is no strong evidence to prove this.


Today i have got my test report for serum creatinine and after taking nephrozone and reduced dose of metformin my serum creatinine is 1.3 mg/dl(1.70mg/dl 25 days back 1.80 35 days back)) and within normal range.


Thanx a lot & will follow your advice Sir.


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