5 reasons you should avoid taking metformin

Metformin (dimethylbiguanide) is a natural product derived from the herbal plant Galega officinalis, known locally as goat’s rue or French Lilac, with the plant being used in Medieval Europe to treat sweet urine. Since then, investigators in the 1800s to the 1900s have begun studying and isolating the plant’s active components. 

In the early 1900s, investigators discovered that the active component of French Lilac called guanidine possesses anti-hyperglycemic effects. However, the investigators found this was too toxic when used clinically. Hence, researchers examined a second active component of the plant called galegine, which is less harmful than guanidine [1]. From galegine, two more products were developed: phenformin and metformin. Both metformin and phenformin are not toxic and can be used clinically. 

What are the uses of metformin? 

Metformin is the first line of treatment for type 2 diabetes (diabetes mellitus). It effectively delays the progression of type 2 diabetes and its complications. In patients with prediabetes, metformin intake prevents the onset of diabetes mellitus. 

Apart from the treatment of type 2 diabetes, this medication has been shown to promote longevity by reducing cardiovascular disease risks and delaying the onset of dementia in those who have type 2 diabetes [2]. 

Currently, metformin is used as an off-label drug for polycystic ovary syndrome (PCOS), preventing weight gain in patients taking antipsychotic medications. An off-label prescription is a medication used to treat illnesses not part of its original intended use. In addition, metformin is currently being investigated as a treatment for Alzheimer’s disease and cancer and as an antiaging drug. 

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What are the side effects of metformin? 

Metformin has minor and more severe side effects that should be considered when taking this medication. 

Minor side effects include the following: 

  • Nausea 
  • Gas 
  • Stomach pain 
  • Heartburn 
  • Diarrhoea

More severe side effects include the following: 

  • Hypoglycemia 
  • Fast heart rate
  • Dizziness 
  • Sweating 
  • Hunger 
  • Drowsiness
  • Headache
  • Feeling jittery or shaking 
  • Weakness 
  • Confusion 

What are the recommended doses for metformin? 

Metformin is available in tablet and oral form and is marketed as an immediate or extended-release tablet. Doses can vary from 500 mg/day to 1,000 mg/day. 

Despite the many therapeutic uses of metformin, here are five reasons why you should not be taking this medication: 

You have renal or kidney failure

Metformin is not metabolized in the body and is excreted unchanged in the urine [3]. The use of metformin is contraindicated in patients with impaired kidney function [4]. Previously, metformin was contraindicated when patients had 1.4 mg/dL or higher (women) or 1.5 mg/dL or higher (men) creatinine concentrations. 

Today, the FDA revised this warning and recommended that metformin be contraindicated in patients with severe kidney failure, defined as eGFR < 30ml/min/1.73m2. Although men and women with moderate CKD can still receive metformin with the latest guideline revisions, those with severe or impaired kidney function should stop taking metformin. However, it has been noted that continuous metformin intake in individuals with moderate CKD could result in metformin-related toxicity. These include minor and adverse side effects and potential lactic acidosis. 

It is believed that since metformin is unchanged in the urine, failing kidneys cannot properly excrete metformin. As a result, metformin accumulates in the blood, causing lactic acidosis. 

One of the immediate side effects of taking metformin following chronic or severe kidney failure includes the development of lactic acidosis, which is a life-threatening complication [5]. 

The following symptoms characterize lactic acidosis: 

  • Stomach or abdominal discomfort
  • Diarrhoea 
  • Fast, shallow breathing
  • Muscle pain or cramping 
  • A general feeling of discomfort 
  • Decreased appetite 
  • Weakness
  • Tiredness 
  • Unusual sleepiness

You have congestive heart failure

Congestive heart failure occurs when the heart muscles do not pump blood efficiently throughout the body. This leads the blood and fluid to backflow to the lungs, which can cause breathing difficulties. Other symptoms of congestive heart failure include oedema or swelling in the legs, fatigue, and tiredness. 

Metformin is contraindicated in patients with congestive heart failure due to the risk of metformin-associated lactic acidosis [6]. 

You have severe dehydration

Severe dehydration due to reduced tissue perfusion can occur when there is an obstruction in the blood flow to the extremities. For instance, patients with oedema in the extremities could suffer from obstruction in the blood flow to the legs and feet, resulting in leg and foot swelling. 

Here are some signs of reduced tissue perfusion by the organ system: 

  • Kidneys: anuria (failure to produce urine) or oliguria (very little urine) 
  • Gastrointestinal: hypoactive or absent bowel sounds, nausea
  • Extremities: oedema, altered sensation, integrity, temperature and skin colour 
  • Cerebral: dizziness, anxiety, syncope, confusion or altered mental status
  • Cardiopulmonary: hypotension

Metformin is contraindicated in patients with reduced tissue perfusion since this can likewise lead to metformin-associated lactic acidosis. 

You have liver disease

Metformin acts in the liver by decreasing gluconeogenesis or the production of glucose. The drug inhibits gluconeogenesis by blocking an enzyme called pyruvate carboxylase [7]. Once this enzyme is inhibited, the first step to building glucose is also stopped. When this enzyme is blocked, it leads to the accumulation of lactic acid. 

Patients with type 2 diabetes frequently have abnormal results in liver function tests due to fatty liver. However, fatty liver in itself is not contraindicated when taking metformin. 

Taking metformin can increase the risk of metformin-associated lactic acidosis, which in turn can harm the individual’s health. 

You are an older individual 

Individuals 65 years old and above are at increased risk of developing long-term conditions such as liver disease and impaired renal function. It has been shown that as one age, renal blood flow and glomerular filtration rate also decrease. Although the amount of decrease varies between individuals, decreased renal function means that metformin is not sufficiently excreted in the urine, leading to metformin-associated lactic acidosis. 

Individuals with type 2 diabetes can have complications when the disease is uncontrolled or not appropriately managed with medications. These include cardiovascular diseases, kidney disease and other conditions where metformin is contraindicated. This makes the management of these individuals challenging. Hence, you must consult your doctor once you develop cardiovascular diseases, liver disease or kidney impairment while on metformin. 

Longevity and metformin 

Metformin is contraindicated in many health conditions. However, taking this medication while in the prediabetes stage is critical in preventing the complications arising from poor disease management. Hence, talking to your doctor about metformin intake in the early prediabetes stage could help improve overall health and outcome. 

Almost all individuals aim for better health and longevity. Taking medications and supplements that promote longevity is essential in controlling one’s health and well-being. Metformin has been shown as a potential antiaging drug. While this medication treats type 2 diabetes, it can also increase life and health span when used correctly and appropriately. 

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You can begin by talking to your doctor about metformin and ensure that you take the medication as prescribed and use the correct dosage. This will help reduce your risk of developing diseases where metformin is contraindicated. 

Choosing the right supplement and medication to promote better health and increase lifespan begins by learning more about the prescription or supplement. 

Metformin is an effective drug for type 2 diabetes by lowering blood sugar levels in the blood. This prescription may also be used as an antiaging medication. However, care should be taken when ingesting metformin as an antiaging since there are not enough studies to support the safety and tolerability of metformin as an antiaging agent. 

Finally, you can achieve longevity by staying informed of the latest developments in drugs that can potentially delay aging, such as metformin. 

[1] https://wchh.onlinelibrary.wiley.com/doi/full/10.1002/pdi.606
[2] https://pubmed.ncbi.nlm.nih.gov/34421827/ 
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3651676 
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5797060/ 
[5] https://pubmed.ncbi.nlm.nih.gov/21989078/ 
[6] https://diabetesjournals.org/spectrum/article/22/1/18/2258 
[7] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4264704 

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