I took metformin for a week and this happened

I admit it…

I took metformin for a week, the leading prescribed drug for treatment of type 2 diabetes in the United States and taken by 80 million people around the world.

This medication is often touted as a wonder drug for individuals with type 2 as well as for those living with other health challenges.

My reasons for taking metformin were highly personal…

I have a genetic predisposition for both prostate cancer and type 2 diabetes (I’m not diabetic but I swing in and out of pre-diabetes), and I’m getting older. I did copious amounts of research, and it seemed, on all three counts (prostate cancer prevention, managing diabetes (increasing insulin sensitivity) and anti-aging), that metformin could truly be a wonder drug.

So, truth be told, I really wasn’t looking at metformin as a drug — I was looking at it more as a “superfood.”

However, I quickly changed my mind, and here’s why…

Peak Prostate Support

Men are less attentive to their health than they should be. Here are signs to be aware of:
    • Uncomfortable urgency
    • Weak urine stream
    • Burning sensation in your groin
    • MORE⟩⟩


How does metformin work for type 2 diabetes?

Metformin is designed to help control the amount of glucose (sugar) in your blood by reducing the amount of sugar you absorb from your food and the amount of glucose made by your liver. Metformin also increases your body’s response to insulin, a natural substance that controls the amount of glucose in the blood. People who have type 1 diabetes, however, do not produce insulin and therefore should not use metformin.

People with type 2 diabetes are prone to developing serious complications, such as kidney problems, diabetic neuropathy, heart disease to name a few. Use of metformin, along with lifestyle changes (e.g., diet, exercise, not smoking) and routine monitoring of blood sugar can help prevent these life-threatening issues.

What are the health benefits of metformin?

I’ve already mentioned that metformin can be effective in controlling blood glucose levels. But what if you’re like me — swinging in and out of prediabetes?

The Diabetes Prevention Program Research Group conducted a randomized clinical trial among adults at high risk for type 2 diabetes and examined the impact of either lifestyle intervention or treatment with metformin on the prevention or delay of diabetes onset. Lifestyle changes (low-fat, low-calorie diet plus 150 minutes of moderate exercise weekly) resulted in a 58 percent reduction in the development of type 2 diabetes, while use of metformin alone reduced diabetes incidence by just 31 percent – which is pretty good but nowhere near the benefits from just making lifestyle changes!

The kicker here though is that the benefits of taking metformin and making the lifestyle adjustments were not cumulative, so making the lifestyle adjustments alone should be the first priority.

But metformin can do more…

Take prostate cancer, for example. A recent study found that metformin could be a useful complementary treatment, especially in men using androgen deprivation therapy (ADT). Metformin appears to work directly on the prostate tumor as well as helping to lower insulin levels throughout the body.

More generally, metformin can suppress tumor growth, enhance the activity of anticancer medications, and improve immunity. This latter benefit is associated with the ability of metformin to lower blood sugar by improving insulin receptor sensitivity. The drug can reduce the fuel supply for bacteria, viruses, and fungi, which tends to reduce one’s susceptibility to infections.

Related: 4+ reasons diabetics should eat mushrooms

Metformin can also help with weight loss. This benefit comes in handy not only among men who are struggling with type 2 diabetes but those who simply need to drop some excess weight. Results of the BIGPRO 1 trial showed that use of metformin was associated with a decline in bad cholesterol (low-density lipoprotein, LDL) concentration when compared with placebo and a decrease in damage to artery linings, a characteristic that contributes to the complications associated with type 2 diabetes (i.e., damage to the eyes, kidneys, and nerves). Other benefits of metformin include a decline in total cholesterol, free fatty acids, and tissue plasminogen activator antigen, all of which are associated with cardiovascular complications.

Peak Prostate Support

10 Targeted Nutrients to Support a Healthy Prostate!


Metformin and life extension

Some research has even suggested metformin may help extend lifespan. The potential life-extension benefit goes something like this: metformin inhibits a complex called mammalian target of rapamycin (mTOR), which regulates the production of protein, boosts energy production, and creates waste. Metformin can help keep mTOR levels from being elevated too much or too often (situations associated with inflammation and cancer growth), which in turn can contribute to longevity.

Related: This anti-diabetes antioxidant reverses insulin resistance

What are the side effects of metformin?

Side effects associated with starting use of metformin can include nausea, vomiting, bloating, diarrhea, and stomach pain. These side effects typically fade as individuals become accustomed to the drug. Metformin should not be taken if you have a history of liver or kidney disease or of congestive heart failure. Anyone with a history of alcohol abuse also should avoid taking metformin because serious lactic acidosis may develop.

People with diabetes are encouraged to exercise regularly, yet use of metformin may interfere with this activity. A study published in Diabetes Care reported that “metformin has the potential to lower some patients’ selected exercise intensity” and also tends to increase heart rate.

The combination of using metformin and exercising may also result in another complication. Use of metformin reduces levels of blood glucose, but exercise can increase levels of the hormone glucagon, which deals with low blood sugar. The combination of metformin and exercise can result in significantly elevated concentrations of glucagon as the body attempts to compensate for the impact of metformin. One result is a less than effective result at lowering the glycemic response after eating than is possible by taking metformin alone.

In addition, the results of at least one small study suggest that use of metformin may lower sex drive and testosterone levels. Given the intense interest among men in their testosterone levels and the desire to boost them, these side effects are not welcome as well.

A total of 64 men with type 2 diabetes were evaluated: 30 who were taking metformin and 34 taking sulfonylurea. Twenty-seven nondiabetic men served as controls. Use of metformin was associated with a significant reduction in testosterone levels, libido, and low testosterone-induced erectile dysfunction, while use of sulfonylurea was associated with a significant elevation in all three factors.

Related: A simple step to stop diabetes

Continued use of metformin also is associated with a reduction in vitamin B12 absorption. Since absorption of this nutrient declines with age, the addition of metformin to the picture can make it worse. A decline in B12 concentrations can cause an elevation in homocysteine levels (which is a risk factor for cardiovascular disease, especially among people with type 2 diabetes), and this decrease in B12 values can grow over time. Low concentrations of B12 are associated with changes in mental function, neuropathy, and anemia.

Peak Prostate Support

10 Targeted Nutrients to Support a Healthy Prostate!


What side effects did I personally experience?

Ok, so you know the TV ads for drugs right – 5 seconds on the actual drug and 5 minutes on the side effects. I get it, drugs have side effects and they spend all that time telling you what they are for one reason, to avoid legal liability. It’s a fact – as long as they TELL YOU you can die from taking a drug you can’t sue them if you die – that’s America for you!

Some of the known side effects of metformin are above – but for me, one week on the drug was enough – notwithstanding all the purported health benefits. Here’s what I personally experienced:

  1. A 5lb weight loss in a week that was unexplained by any other reason;
  2. Constant nausea and lightheadedness;
  3. Massive fatigue and low energy – basically resulting in me being unable to finish basic workouts;
  4. Muscle weakness – I was lifting only ~75% of my normal weights and they were even feeling heavy;
  5. Low motivation and anxiety;
  6. Sleepiness by 8pm – normally I don’t feel like going to bed until after 10.30pm;
  7. Lack of breath – just climbing stairs had me puffing;
  8. Heart palpitations; and
  9. Constant dry mouth.

If it had just been one or two of the above I may have sucked it up, but all of them together felt like a sledgehammer — especially when I was in the middle of training for some pretty intense Spartan and other obstacle course races. All of my training partners were looking at me wondering what the heck was wrong with me!

So I quit.

Did I give up on all the great benefits I was seeking — prostate cancer prevention, improving insulin sensitivity and anti-aging? No way!

I just doubled down on these natural therapies. Here’s how it went for me

Editor’s note: Are you feeling unusually tired? You may think this is normal aging, but the problem could be your master hormone. When it’s not working, your risk of age-related diseases skyrockets. To reset what many call “the trigger for all disease” and live better, longer, click here to discover The Insulin Factor: How to Repair Your Body’s Master Controller and Conquer Chronic Disease!


  1. Al-Kuraishy HM, Al-Gareeb AI. Erectile dysfunction and low sex drive in men with type 2 DM: the potential role of diabetic pharmacotherapy. Journal of Clinical and Diagnostic Research 2016 Dec; 10(12): FC21-FC26
  2. BenGreenfieldFitness. The dark side of metformin: a longevity wonder drug that promises to extend life for a nickel a pop.
  3. Boule NG et al. Metformin and exercise in type 2 diabetes. Diabetes Care 2011 Jul; 34(7): 1469-74
  4. Charles MA, Eschwege E. Prevention of type 2 diabetes: role of metformin. Drugs 1999; 58 Suppl.1:71-73
  5. Choi BK et al. Green coffee bean extract improves obesity by decreasing body fat in high-fat diet-induced obese mice. Asian Pacific Journal of Tropical Medicine 2016 Jul; 9(7): 635-43
  6. de Jager J et al. Long term treatment with metformin in patients with type 2 diabetes and risk of vitamin B-12 deficiency: randomized placebo controlled trial. BMJ 2010; 340:c2181
  7. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New England Journal of Medicine 2002 Feb 7; 346:393-403
  8. Fontbonne A., Charles MA, Juhan-Vague I, et al. The effect of Metformin on the metabolic abnormalities associated with upper body fat distribution. Results of the BIGPRO 1 trial. Diabetes Care 1996; 19:920-6.
  9. Kondo T et al. Vinegar intake reduces body weight, body fat mass, and serum triglyceride levels in obese Japanese subjects. Bioscience, Biotechnology, and Biochemistry 2009 Aug; 73(8): 1837-43
  10. Krawinkel MB, Keding GB. Bitter gourd (Momordica charantia): a dietary approach to hyperglycemia. Nutrition Reviews 2006 Jul 1; 64(7): 331-37
  11. Merck. The Merck Manual of Diagnosis and Therapy. Section 2. Endocrine and Metabolic Disorders. Chapter 13. Disorders of Carbohydrate Metabolism
  12. Panahi Y et al. Curcuminoids modify lipid profile in type 2 diabetes mellitus: a randomized controlled trial. Complementary Therapies in Medicine 2017 Aug; 33:1-5
  13. Shishehbor F et al. Vinegar consumption can attenuate postprandial glucose and insulin responses; a systematic review and meta-analysis of clinical trials. Diabetes Research and Clinical Practice 2017 May; 127:1-9
  14. Statista. Leading prescriptions dispensed in the US diabetes market 2017
  15. Whitburn J et al. Metformin and prostate cancer: a new role for an old drug. Current Urology Reports 2017; 18(6): 46
  16. Wong S. Study reveals the gut’s role in effects of diabetes drug. Imperial College London 2016 Apr 6
Craig Cooper

By Craig Cooper

Craig Cooper is a serial entrepreneur, venture capitalist, author, and TV host of CNBC's "Adventure Capitalists". He is an “Ambassador” for both the global men’s health foundation “Movember” and 2XU, the performance sportswear company. He is the author of the Harper Collins book “Your New Prime: 30 Days to Better Sex, Eternal Strength, and a Kick-Ass Life After 40“. Follow Craig on Instagram @craigcooperrrr and Facebook.