What is prediabetes and why does it matter?

When I’m seeing a new patient, I am especially alert to certain pieces of their history. Do they have a strong family history of diabetes? Are they of Latino, Asian, Native-American, or African-American ethnicity? Did they have diabetes in pregnancy? Are they overweight or obese? Do they have polycystic ovarian syndrome (PCOS)?

Why do I care about these things? Because they may be clues that the patient is at risk for developing adult-onset (type 2) diabetes, and that can lead to multiple major medical problems.

Many people have heard of type 2 diabetes, a disease where the body loses its ability to manage sugar levels. Adult-onset diabetes most often affects people with known risk factors and can take years to fully develop, unlike juvenile (type 1) diabetes, which can develop randomly and quickly.

Here is why high blood sugar is a problem

Untreated or undertreated diabetes means persistently high blood sugars, which can cause horrible arterial blockages, resulting in strokes and heart attacks. High blood sugars also cause nerve damage, with burning leg pain that eventually gives way to numbness. This, combined with the arterial blockages, can result in deformities and dead tissue, which is why many people with diabetes end up with amputations. The tiny blood vessels to the retina are also affected, which can cause blindness. And don’t forget the kidneys, which are especially susceptible to the damage caused by high blood sugar. Diabetes is a leading cause of kidney failure requiring dialysis and/or kidney transplant. But wait! There’s more. High blood sugar impairs the white blood cell function critical to a healthy immune system, and sugar is a great source of energy for invading bacteria and fungi. These factors put folks at risk of nasty infections of all kinds.

These facts scare me. Not just because I’m the doctor who gets to help manage these not-fun issues, but because I’m of Latina descent and diabetes runs in my own family. I’m at risk too.

So, what can we do? If we know who is at risk for diabetes, and it takes years to develop, we should be able to prevent it, right? Right!

Keeping prediabetes from becoming diabetes

A recent in-depth article by endocrine experts declares prediabetes a worldwide epidemic (which it is).1 Prediabetes is defined by fasting blood sugars between 100 and 125, or an abnormal result on an oral glucose tolerance test. What can we do to treat prediabetes? The authors reviewed multiple large, well-conducted studies, and all showed that prediabetes can be targeted and diabetes delayed or prevented.

One of the largest studies was conducted here in the U.S.2 Over 3,000 people from 27 centers who were overweight or obese and had prediabetes were randomly assigned to one of three groups:

  1. standard lifestyle recommendations plus the medication metformin (Glucophage);
  2. standard lifestyle recommendations plus a placebo pill;
  3. an intensive program of lifestyle modification.

The intensive program included individualized dietary counseling, as well as instruction to walk briskly or do other exercise for 120 minutes per week, with the goal of some modest weight loss.

Investigators followed the subjects over three years, and the results were consistent with those from many other studies: the people in the intensive lifestyle modification group (nutrition counseling and exercise guidance) were far less likely to develop diabetes in that time span than those in either of the other groups.3,4,5 Want numbers? The estimated cumulative incidence of diabetes at three years was 30% for placebo, 22% for metformin, and 14% for lifestyle modification. The incidence of diabetes was 39% lower in the lifestyle modification group than in the metformin group. As a matter of fact, they shut down the study early because it was deemed unethical to keep the subjects in the placebo and metformin-only groups from proper treatment.

The authors of the prediabetes review also looked at the multitude of other studies that more closely examined what kinds of diets are useful and concluded that “The consensus is that a diet rich in whole grains, vegetables, fruit, monounsaturated fat, and low in animal fat, trans fats, and simple sugars is beneficial, along with maintenance of ideal body weight and an active lifestyle.”

It’s really just common sense. And that’s why my husband and I greatly limit our intake of sugar and carbs, get four-plus servings of plant-based foods daily, and exercise.

A word about medication

For my patients who for whatever reason cannot change their diet and lifestyle, I do recommend a medication. For patients who are on the cusp of diabetes and who have multiple risk factors or other diseases, medication really is indicated. There are also people who want to add a medication to diet and exercise in order to boost weight loss and further decrease their risk, and that’s fair as well.

I know that using medications for prediabetes is controversial. Other doctors have warned that the label “pre-diabetes” is over-inclusive and that it’s all a vast big-pharma marketing scam.6 It’s true that we have to be informed about what we’re prescribing and why. But based on what I’ve seen in my career, I definitely do NOT want to develop diabetes myself, and if you’re at risk, believe me, you don’t either. So, consider the pros and cons of everything, talk to your doctor, and decide for yourself what action you want to take. And then, take action.


  1. Edwards CM, Cusi K. Prediabetes: A Worldwide Epidemic. Endocrinology and Metabolism Clinics of North America, December 2016.
  2. Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New England Journal of Medicine, February 7, 2002.
  3. Pan XR, Li GW, Hu YH, et al. Effects of diet and exercise in preventing NIDDM in people with impaired glucose tolerance. The Da Qing IGT and Diabetes Study. Diabetes Care, April 1997.
  4. Tuomilehto J, Lindstrom J, Eriksson JG, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. New England Journal of Medicine, May 3, 2001.
  5. Lindstrom J, Peltonen M, Eriksson JG, et al. Improved lifestyle and decreased diabetes risk over 13 years: long-term follow-up of the randomised Finnish Diabetes Prevention Study (DPS). Diabetologia, February 2013.
  6. Prediabetes: can prevention come too soon? Blog post by Richard Lehman, Cochrane UK Senior Fellow in General Practice, November 11, 2016.

Related Information: Starting to Exercise


  1. Rhonda Witwer

    Low carb eliminates resistant starch, which has been shown in 9 clinical trials to significantly improve insulin sensitivity in prediabetics. It is in intact whole grains (but not refined grains), under-ripe green bananas, beans & peas. It is also available as a supplement, which was used in all of those 9 clinical studies. In December, the FDA approved a qualified health claim that resistant starch reduces the risk of type 2 diabetes based upon those clinical trials. For more information, see http://resistantstarchresearch.com/posts/fda-announces-health-claim-for-resistant-starch/

    I agree with you completely on eliminating refined carbohydrates, but the data is overwhelming that you should be adding resistant starch to your diet, not eliminating it.

  2. Selma Öztürk

    Prediabet should be recommended for use by phytotherapeutic antidiabetic food supplements (olive leaf, cinnamon, rooibos plant, hawthorn extract, turmeric extract, lipotropic factor etc.), probiotic supplements by doctors and dietitians instead of drugs in the treatment of insulin resistance.
    And complementary medical practices, diet therapy, exercise therapy, cupping therapy, hirudotherapy, ozone therapy, acupuncture should take place in the first level health services. Respect and love
    Dyt.Selma Öztürk

  3. Dawn

    I am pre-diabetes. but my regular Dr is not concerned. I have a low animal fat diet with a lots of veggies and fruits, I exercise regularly more than 120 minutes a week. I am 5.4 and weight 130 pounds not over weight. Other than cholesterol, which is under control with pills, I am generally healthy. However, I am concerned about it and need to know what else I can do to control the blood sugar?

    • Julie Olguin Molina

      Your comment about you Doctor not being concerned is fairly common.

      Buy yourself a Glucometer to test your own blood sugar after meals and
      start walking regularly. Insulin Resistance only responds to regular
      consistent exercise for some people Be sure you have seen an Endocrinologist who can ell you that PREDIABETES IS DIABETES IN
      EARLY STAGES and much can be done if you exercise consistently and
      work with a Registered Dietitian to learn carbohydrate counting and you
      can delay full blown diabetes for many years. Let a Hemoglobin AIC be your guide, it’s a lab test that provides you with an average blood sugar range for the last 3 months. A Registered Dietitian should also be a Certified Diabetes Educator.
      (a lab test that gives you an average over the last 3 months)

  4. Rasika

    The conclusion is spot on: “The consensus is that a diet rich in whole grains, vegetables, fruit, monounsaturated fat, and low in animal fat, trans fats, and simple sugars is beneficial, along with maintenance of ideal body weight and an active lifestyle.”

    Very well written and helpful article!


    Intermittent-FASTING as practised by our early cavemen food-gathering & animal-hunting ancestors can benefit in more ways than 1. It certainly & relatively quickly reduces diabetes-causing obesity to more beneficial levels, I have very recently myself in Malaysia found this out! (Dr. Mercola’s website for more helpful reads!) Practising Buddhist meditation withing its breathing technique can also help obesity & tends to put things in better perspective…GO FOR IT!

  6. Jeremy

    When my fasting blood glucose, which had been 99 for years when checked annually, was over 100 for the first time (133) I quit eating refined carbs. That got it down, but only to 117. Then I gave up nearly all carbs, which is a ketogenic diet. That was 4 years ago. My fasting glucose, without diabetic meds, is now between 75 and 100 every day, my formerly scary lipid profile looks great (despite a high fat intake) and I have lost 50 lbs and kept it off. I don’t know if this can work for everybody, but it certainly works for me. As for long-term safety, a friend of mine has been on a ketogenic diet for 15 years with no visible ill effects at all, and I know many more short-term practitioners who appear to be doing well. Of course that’s just one data point, but unfortunately there are no large bodies of data from well-designed studies out there. Nobody seems to want to finance them. But there are a books, cookbooks and support groups for ketogenic dieting. I recommend the FaceBook group called “Reversing Diabetes.” Some people report improvements in mood, energy level and blood pressure too, though those did not happen for me, but I am quite pleased to have good blood glucose, lipid and weight control without meds.

  7. Donald Morgan

    You should limit your intake of fruits that are heavy in sugar or carbs. Carbs are not for anyone who is overweight, obese, pre- diabetic or diabetic. Carbs are not a essential dietary requirement. Fats and protein are essential. Until we get this message out we will continue to have the confusion on what we should eat and we will stay sick!

  8. Donald Morgan

    Why do we continue to recommend a diet that is high in carbohydrates? Anyone that is insulin resistant, pre diabetic, type 2 diabetic should not be consuming carbohydrates! Seems like we are trying to keep people on medication. Studies show a low carb diet works well in reducing blood glucose levels as well as lowers LDL levels, raises HDL and triglyceride numbers plummet. When will we recognize this?

  9. Thomas Braun RPh

    Great summary of pre-diabetes. Why is there no mention of low Vitamin D blood value also being a predictor of Type II?
    The correlation is there. Boosting vitamin D above 40 ng’s and eliminating excess sugar would go a long way in stopping the epidemic.

  10. Nancy

    A doctor also recommended I try alpha lipoid acid as many patients had had good results with it. My other, regular doctor has been pleased that my blood sugar has not gotten worse over a couple of years. I generally use common sense in what I eat and have walked daily for years but I don’t eat as many vegetables as I should and I do like butter!

  11. Phil

    A low carb high (quality) fat diet combined with fasting works wonders. This is because the problem is one of insulin resistance and good quality fats such a avocado, coconut oil and olive oil don’t spark an insulin response to the extent of carbohydrates. Fasting also serves to improve insulin resistance – people have effectively reversed type 2 diabetes using these strategies – just google Dr Jason FUNG – he is the MAN…

  12. Andy

    Good advice, I have gave up any food that has sugar on it, the result is amazing. It is the new me now. I have more energy, no pain, I’m more awake and alert.

  13. Vince

    Disease creep sometimes called disease mongering is a real problem and it all starts with the belief that everyone needs a pill ;l just a matter of time.What really matters to the patient is what benefit will he accrue and at what risk..here no hard endpoint benefit is shown so exactly how many less C]] heart attacks; strokes and numerous other bad events happened in each group. How many deaths where prevented…..handing out a pill should be reserved for those who you can actually show a real benefit for eexactly where do you draw the line for prediabetes; you know many ‘good ideas’ simply where not. In these patients what where the A1c levels and how low where they reduced to.

  14. J Tatnall

    With dietetic counseling, continued exercise, and real life style food changes, I have lost nearly 100 lbs, and have across the board normal levels now. I am a believer in Michael Pollan’s advice, ” Eat food, mostly plants, not too much.” Real food, cook it yourself. Know what you’re eating.

  15. George

    I mix 2 table spoons of apple cider vinegar with water and drink it every night, walk for two hours(10000 steps) at least, no sugar, very low carbs to keep my blood sugar levels under 120. Simple but it works very well. Trying to keep my BMI close to 25.
    George from hotroomz.com

  16. Frank

    I’d be very interested in hearing Dr. Tello expand on what she means by “greatly limit our intake of sugar and carbs.” I know many prediabetics and Type 2 diabetics who follow very low-carb diets in order to keep their blood sugar numbers down. As a borderline prediabetic myself, I’ve found that even whole grains and fruit may cause significant blood glucose spikes, depending on how much and how they are eaten, so for me they do not necessarily get a free pass. I’d be interested to know if Dr. Tello has an opinion on how low it is safe/appropriate to go in setting how much carb (of any kind) to eat as a percentage of daily calories.

  17. Azhar jamil

    I also have a family history of diabetes. But I think prediabetes can be prevented successfully just changing one’s lifestyle, and everyone, at risk can do it easly.
    After fourty’s a restricted diet, regular walk and limited sexual relationship with your life partener(if family is completed there might be no need) to live a healthy remaining life.
    Diabetes is a very potent disease, it’s a change in human body just due to an age factor. We made it worst with our attitude.

    • Dammi

      What do you mean by “limited sexual relationship with your Life partner”? How can THAT help reducing one ‘s risk of developing type 2 diabetes??? By the way, physical intimacy with one’ s partner is not simply to” complete family “. There are actually many health benefits – physical and mental – of safe love making with one ‘s life partner.

  18. andy

    I think every third person is suffering with diabetes these days due to our unhealthy lifestyle and lack off proper knowledge. Prediabetes is one of the best method to keep ourselves safe. Thanks for this wonderful resource.

    • Donald Morgan

      They just need to drop the low fat diet. That’s what got us into trouble in the first place. To be healthy and avoid these chronic illnesses, lower the carbohydrate intake and increase physical activity. This is not a mystery, there are humans today that do not get the western diseases we do. The eat more fat, low carb and exercise more!

  19. Gerald

    Very well said. I have a family history of diabetes and try to follow the lifestyle changes you recommend, but also use the dietary supplement alpha lipoic acid. It has been shown in many studies the lipoic acid improves insulin sensitivity and protects the peripheral and optic nerves from diabetes related degeneration. To get the maximum effect I use a solubilized high bioavailability product (thiogel). I’ve been taking 200 mg/day for almost 20 yrs and at 81 yrs, I don’t show any signs of Type 2 diabetes.

  20. Emily

    “And that’s why my husband and I greatly limit our intake of sugar and carbs…”

    I would emphasize limiting intake of “refined carbs,” not carbs in general. Of course, some of the best foods for prediabetes, which you listed, are carbs (whole grains, vegetables, fruit).

Commenting has been closed for this post.