How to Prevent Prediabetes from turning into Diabetes

Image Credit: Heather Aitken / Flickr. This image has been modified.

Drugs vs. Lifestyle for Preventing Diabetes

In just one decade, the number of people with diabetes has more than doubled. According to the Center for Disease Control and Prevention, by 2050, one out of every three of us may have diabetes.

What’s the big deal?

Well, the “consequences of diabetes are legion.” Diabetes is the number one cause of adult-onset blindness, the number one cause of kidney failure, and the number one cause of surgical amputations.

What can we do to prevent it?

The onset of Type 2 diabetes is gradual, with most individuals progressing through a state of prediabetes, a condition now striking approximately one in three Americans, but only about one in ten even knows they have it. Since current methods of treating diabetes remain inadequate, prevention is preferable, but what works better: lifestyle changes or drugs? We didn’t know until a landmark study, highlighted in my video, How to Prevent Prediabetes from Turning into Diabetes, was published in the New England Journal of Medicine.

Thousands were randomized to get a double dose of the leading anti-diabetes drug, or diet and exercise. The drug, metformin, is probably the safest diabetes drug there is. It causes diarrhea in about half, makes one in four nauseous, about one in ten suffer from asthenia (physical weakness and fatigue), but only about 1 in 67,000 are killed by the drug every year.

And the drug worked. Compared to placebo, in terms of the percentage of people developing diabetes within the four-year study period, fewer people in the drug group developed diabetes.

But diet and exercise alone worked better. The lifestyle intervention reduced diabetes incidence by 58 percent, compared to only 31 percent with the drug. The lifestyle intervention was significantly more effective than the drug, and had fewer side effects. More than three quarters of those on the drug reported gastrointestinal symptoms, though there was more muscle soreness reported in the lifestyle group, on account of them actually exercising.

That’s what other studies have subsequently found: non-drug approaches are superior to drug-based approaches for diabetes prevention. And the average 50 percent or so drop in risk was just for those people instructed to improve their diet and lifestyle, whether or not they actually did it.

In one of the most famous diabetes prevention studies, 500 people with prediabetes were randomized into a lifestyle intervention or control group. During the trial, the risk of diabetes was reduced by that same 50-60 percent, but only a fraction of the patients met the modest goals. Even in the lifestyle intervention group, only about a quarter were able to eat enough fiber, meaning whole, plant foods, and cut down on enough saturated fat, which in North America is mostly dairy, dessert, chicken and pork. But they did better than the control group, and fewer of them developed diabetes because of it. But what if you looked just at the folks that actually made the lifestyle changes? They had zero diabetes—none of them got diabetes. That’s effectively a 100 percent drop in risk.

I often hear the diet and exercise intervention described as 60 percent effective. That’s still nearly twice as effective as the drug, but what the other study really showed is that it may be more like 100 percent in people who actually implement the diet and exercise intervention. So, is diet and exercise 100 percent effective or only 60 percent effective? On a population scale, since so many people won’t actually do it, it may only be 60 percent effective. But on an individual level, if you want to know what are the chances you won’t get diabetes if you change your lifestyle, then the 100 percent answer is more accurate. Lifestyle interventions only work when we do them. Kale is only healthy if it actually gets into our mouth. It’s not healthy just sitting on the shelf.


How about preventing prediabetes in the first place? See Preventing Prediabetes By Eating More and my video How to Prevent Prediabetes in Children.

Some things we may want to avoid can be found in my videos Eggs and Diabetes and Fish and Diabetes.

And what if we already have the disease? See Diabetics Should Take Their Pulses and my live presentation From Table to Able: Combating Disabling Diseases with Diet.

What if you don’t have time for exercise? Check out Standing Up for Your Health.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

39 responses to “Drugs vs. Lifestyle for Preventing Diabetes

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  1. I have enjoyed all of the articles and videos on this site. I am healthier now then the past thirty years of my life. I feel great,bike ride15 miles per day. My triglycerides are almost non-existent. My physician nearly does back flips after checking my blood tests and so on. It is a pleasure having an informative physician educating so many.

    1. Yay for you being the picture of health as you age! Is your doctor curious about your diet and exercise habits so s/he can share your success with other patients? Hope so. I think some docs consider folks like you to be “anomalies” and don’t believe that if they supported their patients with nutrition and movement counseling, they, too, could achieve your results.

    2. That is awesome! Keep up the good work and spread the knowledge to not only your physician but to you friends/family!

  2. As a side note, just thought I’d mention this smaller/shorter study where oral curcumin supplementation prevented pre-diabetics from becoming diabetic (16.4% in the placebo group vs 0% in the curcumin group over a period of 9 months). In his book How Not To Die, Dr. Greger says that he prefers whole turmeric to curcumin extracts due to possibly greater overall efficacy/safety. The best choice, of course, is to adopt a healthy life style with plenty of exercise that includes foods with amazing health-promoting properties such as turmeric.

  3. I really wish the title of your article would clarify this being for type 2 diabetes. I feel like by not clarifying you are contributing to misinformation about type 1 diabetes.

    1. No, there is not misinformation here. This information can also help you if you have Type 1 diabetes. If you have spent a lifetime dealing with Type 1 diabetes, I am sure that you feel there is no way that you can improve the overall outlook of your disease, but you can.

      Dr. Campbell wrote in his book, “The China Study”, “Type 1 diabetics cannot produce insulin. It is difficult to imagine any dietary change that might aid their predicament. But after just three weeks, the Type 1 diabetic patients were able to lower their insulin medication by an average of 40%! Their blood sugar profiles improved dramatically. Just as importantly, their cholesterol levels dropped by 30%! 15 Remember, one of the dangers of being diabetic is the secondary outcomes, heart disease and stroke. Lowering risk factors for those secondary outcomes by improving the cholesterol profile is almost as important as treating high blood sugar.”

      You may not be able to completely discontinue taking insulin, but you will greatly improve your health by switching to a whole food plant based diet. Make sure you search for “amla” here at, I have found it to be a remarkable little fruit.

      You can look at the many videos on this website, you can buy Dr. Greger’s new book, and you can also go to to find specific dietary changes you can make to improve your blood sugar.
      Take Care!

    2. Hi L, sorry for the misunderstanding, but in the article he does mention specifically that he’s referring to type 2 diabetes. Just reading the title by itself without reading the article isn’t meant to be helpful. Please let us know if you have any other questions or comments. Thanks!

      1. Why is there a misunderstanding? Type 1 diabetics also benefit from this dietary change and they can lower the amount of medication they are taking.

        1. Hi 2tsaybow,
          The article is about preventing type 2 diabetes, not prevention or treatment of type 1 diabetes. That being said, I absolutely agree with you that healthy dietary/lifestyle changes can be helpful for type 1 diabetics!

          1. I know why you responded the way that you did, but reading the article and changing to a WFPB diet is beneficial for someone who has Type 1, right? So there is no misinformation because Type 1 diabetics will benefit and “L” should know that a WFPB diet offers a beneficial change for her/his circumstances.

            Here’s a mantra for you: “This is a way of eating that is beneficial to all.”

            Say that before you respond, because it is true. Everyone, everything, everywhere benefits when we quit eating animal products. This is a change that heals people and if adopted widely it will heal, nay save, our entire planet.

            So when someone say’s: But it’s not for my specific disease so there’s a problem, you need to offer proof to them that it is for their disease, because it is.

  4. What no medical doctor who runs a Web page ever mentions: I am a vegan and I am normal weight and I have diabetes. I have to take insulin. Vegetable/vegan diet has not reduced my blood glucose spikes after eating, nothing has. Not even exercise.

      1. No Sir, Type 2. I am 74, male, 5’8, 150 lbs. I have had diabetes for 15 years. I used to control it with diet and exercise but it has gone ‘wacko’ and I have to take insulin. I tried to ‘teach’ my liver to control (reduce insulin intake)l the insulin but has not worked–stupid thing to do. When I do this, I go from 5.8 A1C to 7. Medicare refuses insulin pump because the pancreas levels are ‘high normal’ and Medicare will not approve.

        1. Disclaimer: I do not have diabetes (either type) nor am I a medical professional of any kind. The following is based on my reading, I mean no offense.

          Do you know what your % fat intake is? Insulin resistance is caused by elevated free fatty acids (FFA) in the blood, and it doesn’t matter if the FFA enter the blood via animal products or plants. If your diet is vegan, but not low fat, that might not be good enough.

          Here the website of someone who has had success in increasing insulin sensitivity of both type one and type two diabetics. Increased insulin sensitivity means less insulin is required.

          Essentially he puts clients (whether T1 or T2) on a very low fat, high whole foods vegan diet. T2 can sometimes be reversed on the diet, but even T1’s find they need less insulin.

        2. Only personal anecdote here sir, but I am 63 and no longer diabetic after being diagnosed in the early 2000’s. After struggling with solutions, it was going whole food plant based AND especially keeping fats under 10% that worked for me to finally get my numbers normalized. That essentially means no added fat of any kind. Since you are slim this may not apply to you and we have some type 1.5 diabetics here somewhere who can perhaps chime in? From what I gather it seems to be a form of an autoimmune delayed type 1 where the pancreas still has some function but not enough to maintain glucose control? A little research and cautious trial and error are my best tools, but everyone is different, good luck!

  5. I’ve been a vegetarian (almost vegan in that I rarely eat dairy or eggs) for most of my life. I’m a healthy vegetarian i.e, no junk food but rather I eat whole foods cooked at home. For the last 3 years I’ve tried not to exceed 25 g of sugar per day from any source (e.g. I don’t eat white potatoes). I exercise daily. I don’t drink or smoke. The point of these statements is a lead up to my question – for the last 18 months I’ve had significant stress levels, sleep deprivation and insomnia brought on by the constant nocturnal noise from my upstairs neighbours. No amount of reasoning works with them. I’ve read that sleep deprivation can cause Type II diabetes. Am I at risk? Is all my nutritional hard work for nothing if I still get disease?

    1. Hi Daisy. There are a number of factors that affect your risk for diabetes, including genetics and other factors over which you have no control. It is the combination of these factors with the lifestyle factors that you can control, like diet and exercise, that determine your overall risk for developing Type II diabetes. Great job minimizing the risk factors that you can control! Please don’t let your neighbors being inconsiderate let you feel like your hard work is all for naught.
      Though you are doing a great job of eating right and exercising, stress and sleep deprivation can certainly contribute to the development of disease, so I’d recommend focusing some of your efforts on stress reduction techniques. Consider developing a yoga or meditation practice, as both of these can help to minimize your stress response (even to the noisy neighbors outside of your control!) and may even Affect Cellular Aging. I’d also encourage you to evaluate your sleep hygiene, as some simple steps like limiting screen time before bed may help to improve your sleep.
      Dr. Greger stresses the importance of sleep in the videos Sleep & Immunity and Optimal Sleep Duration. Interestingly, Kiwifruit has been shown to improve symptoms of insomnia, and Dr. Greger posted a video a while back highlighting Foods with Natural Melatonin. I hope this helps (and your noisy neighbors move)!

  6. I am prone to type 2 diabetes and when I weighed 205 lbs I took 1000 mg of metformin daily. Four years ago I started on a vegan diet and lost weight. I am 5’8″ and now have my weight in the 160’s. I quit the merformin, My glucose level has been as low as 94 in the morning and after an hour of aerobics and an hour spinning (cycles), my glucose rises to 125, but falls back to around 100 later in the day. I want to lose a few more lbs after reading about fat around the liver and pancreas to see if that improves my insulin resistance.

    1. Give it a try Walt. I also dropped a ton and reversed diabetes and slew of other issues years ago and have never felt better! It just ticks me off it was such a buried treasure then because I could have prevented a lot of issues had I known earlier! With the diabetes issue I find it is really important to be militant about fat intake and have to keep it low to get good results…no added fat of any kind, and even have to watch my intake of whole foods high in fat. Whenever I see people on “other” websites talking about “good fats-bad fats” and the conversation is about coconut OIL versus olive OIL or canola OIL, or especially butter, it makes me want to scream! If a low fat, whole food plant based diet can reverse diabetes and heart disease, the only good fat is what comes prepackaged in plants, not in a bottle, and certainly not in a stick! We are so successful as a species (depending on how you choose to define success, most other success like us are called vermin!) because of our ability to survive on about anything in times of shortage. Some mistake surviving the ingestion of known problematic, but favored food as health…but it catches up to us!

      1. I was thinking 1.5 also, but my pancreas operates ‘high normal’. There is no problem with my pancreas. It just appears to be bodily insulin resistance, and, I am convinced there is a liver ‘malfunction’, albeit, the liver tests come back ‘normal’. I just don’t get it, irrespective of all my research, the only thing the doctors come up with that it is genetic (lack of answers). My brother and grandmother had diabetes; nevertheless, there is something missing that I am not doing, or could do, to stop taking insulin and bring my body back to normal–I just have not discovered the way to do that, and, may never. Endocrinologist don’t know about alternative health and they have no answers, but neither does my alternative health research. Thanks for your reply.

        1. Have you done a genetics test? Maybe there would be a clue there. The test I had showed several things that would point me toward diabetes, but I’m not diabetic. They do say in the report that a diet low in sugar, refined carbohydrates and saturated and trans fat will reduce risk. They don’t talk about other fats, but perhaps the information about all fats’ role in diabetes is new since my test was done. Of course, this advice is not news to this group.

        2. Rude awakening, I’m really impressed with all your efforts. Have you tried being super strict about getting rid of all added fats and sugars, and fully committing to a whole-food, plant-based diet in addition to regular exercise? The fact that your liver and pancreas are looking normal in tests is great. Your insulin resistance can/should be resolved with the above diet changes. Good luck!

  7. I’ll post this here since it’s more likely to be seen: What does Dr. Greger think of excess manganese consumption? I know he recommends to stay away from too much hibiscus tea because of the manganese, but he might be considering that diets are already high in manganese. To me it’s pretty much unavoidable while following a whole foods plant based diet. I’m eating upwards of 14 servings of fruit and 8 servings of leafy greens (I’m even trying to up this even more) while adding high caloric density foods like legumes and sweet potatoes. Total calories eaten hovers at around 3000 a day, and that’s while being sedentary due to my injury. I put my foods I’m consuming into and it says that I’m eating 14.5mg of manganese give or take. Is that ok? I know how important small things like this can be. I’ve seen the videos on B12.

    1. Drugs can have many side effects, some of which are very detrimental, and so it is important to highlight when lifestyle changes alone can create positive health outcomes.

  8. 2 questions: (of course I would need to consult with my Dr before taking action)

    1) In the article below you talk about drug vs lifestyle as a way to prevent diabetes from progressing, but what about doing both? would it be more effective than just a healthy lifestyle?

    2) Would you recommend low doses of Metformin as a tool for longevity? pro or against it?

    Here’s a couple of articles I found on the subject, containing a lot of medical/scientific jargon

    And on a person note, thanks! I’m new to the whole food plant based diet (just hit my first 30 days milestone, which was EASY), your videos really helped me get more educated

  9. No supplement or medication has ever been objectively shown to increase longevity in a healthy individual that has no deficiencies. On the other hand most/all supplements/medications ingested by healthy individuals have been shown to increase the risk for disease and premature death. Therefore the only recommendation to take a supplement or medication to increase longevity would be if there was more than one well-founded peer-reviewed published study that clearly shows an increase in longevity when ingesting the supplement/medication. As far as diet vs diabetes vs metformin, when eating correctly, type diabetes can be cured (normal blood sugar without medication) therefore there would be no sense in taking a medication that lowers blood sugar when blood sugar is normal.

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