What Causes Type 2 — Genes or Food?

There’s a major split in the Type 2 diabetes world. Some believe Type 2 is all about diet (and maybe exercise.) Others say it’s mostly a genetic illness and that diet doesn’t make much difference. Who’s right?


This disagreement came to the forefront in the controversy over TV chef Paula Deen. When Deen told the world she had Type 2 diabetes, some people blamed the high-sugar and high-fat food she cooks on her shows. (One signature dish is deep-fried cheesecake.)

But Deen denied her diet had much to do with it. She pointed out that many people eat like her and don’t get diabetes. She said her genes were at fault, even though no one else in her family has diabetes.

Bloggers jumped in; some to attack Deen, some to defend her. On Diabetes Self-Management, Jan Chait wrote, “Psst! Food does NOT give you diabetes!”

Some doctors agreed. Dr. Terry Simpson wrote, “It is more a matter of genetics than anything else. For those who are unlucky enough to have the genetic code that predisposes them to diabetes, the odds are they will become its victim… Even the most “in shape” individual, who eats “right” who has the genetics for diabetes can no more avoid that than you can avoid a car accident if someone misses a stop sign because they are texting.”

I beg to differ. Blaming genes without referencing diet makes no sense at all. There has been an increase in diabetes worldwide of 100% to 400% (depending on location) in the last 20 years. Genes don’t change that fast. The environment has changed. People are more sedentary and more stressed now. But the number one change has been the mass consumption of sugars and refined carbs.

Dr. Robert Lustig at University of California San Francisco blames sugars for most of the diabetes increase. Our bodies just weren’t made to eat these highly concentrated carbs, he believes. His research on how different foods like corn syrup (or “corn sugar” as the growers prefer to call it) break down in our bodies seems to show that many sugars cause insulin resistance and liver damage. They’re “poison,” he says.

Why is this important? It matters because, if foods are a main cause of Type 2, diabetes treatment should focus on eating healthier food. Genes clearly play a role, but it’s not true that “genes give you diabetes.” Genes can make you vulnerable to the foods that cause Type 2. But if you avoid those foods, you won’t get it.
Paula Deen isn’t going to change. Her Web site Diabetes in a New Light says she doesn’t plan to make major changes in her lifestyle, although she has started walking with her husband.

Dr. Simpson agrees that diet changes won’t help much. “Food can kill you,” he says, “but it cannot cure you.” But Dr. Simpson is a weight-loss surgeon. He has a vested interest in believing that diet changes don’t work.

The reality, as most of our readers know and many have written in comments, is that diet makes a huge difference in diabetes. Many doctors have found that Type 2 diabetes can be improved and sometimes reversed by stopping sugars and refined carbs, eating more fiber, getting more exercise, and reducing stress.

Dr. Mark Hyman, author of the Blood Sugar Solution, says hundreds of his patients and thousands of readers have gotten off all diabetes medicines just by changing diets and taking some dietary supplements if needed.

In his book The 30-Day Diabetes Cure, cowritten with Jim Healthy, naturopath Dr. Stefan Ripich says he has never had a person with Type 2 who couldn’t get off medicines by changing to a high-fiber, very-low-sugar diet.

And it’s not just doctors with programs to sell who have demonstrated that diet can make all the difference in Type 2. Studies show that a vegan diet (no animal products at all) often enables people to reduce or stop their medicines, possibly because of the high fiber content. You can see some of their success stories at the Physicians Committee for Responsible Medicine Web site.

Very-low-carb diets also seem to greatly improve diabetes, as has been shown in several studies. Dr. Lustig notes that people on the Atkins (low-carb) diet and Japanese people both have very low rates of diabetes. One group eats lots of animal protein, the other very little. The one thing they have in common, says Lustig, is that they eat little or no sugar.

In my view, the evidence for a dietary cause of Type 2 diabetes is overwhelming. Stress, genetic background, and lack of physical activity are also very important. But you can’t change genes, and stress reduction is a lifelong effort. The dramatic results many people achieve by coming off refined carbohydrates and sugars certainly make one of the approaches I mentioned worth trying. What do you think?

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  • Deb

    I certainly agree that there is a dietary component to T2, but I think there are many genetic factors at play, just as there are in many other conditions. When I was diagnosed with prediabetes, I was on a vegan diet, not eating any refined carbohydrates and almost no sugars. (I’m a sours kind of gal; my husband is the one who goes for the sweets and continues to eat them despite his diabetes.) Because both of us have T2, our daughter is at greater risk than I was, since only one of my ancestors had it.
    Dramatic results seem to come from a number of dramatic changes: coming off refined carbs and sugars; having gastric bypass surgery; adopting a strict exercise plan. Again, there appear to be many factors at play besides diet.

  • jim snell

    Interesting review and covering the differing views.

    I believe from my searching, readings and getting my own mess – rot stopped ( and I hesitate to say cured); there is a number of factors that seem to drive type 2 diabetes.

    First off; the human body – a la Hunter gatherer digestion gene system has no energy balance control built in that would if there would bypass extra glucose/calories in intestines if body skeletal muscles temporary glucose storage are overwhelmed – loaded to the hilt. This old system was optimized to prevent stravation/extend life as far as possible and extract every calorie from the low grade low avaialbility of food in the early days and dump every bit of glucose extracted/saved and dump in the blood system.

    Todays 24/7 availability of generous amounts of grains, flours, sugars play a key role coupled with all the labour/brain energy saving cars, lap top computers, video games, wide screen tv and assorted couch potato tools and entertainment.

    Food and calorie restriction and control obviously play an important role in stopping the rot. Look at all the curious results under bariatric surgery, lap band, starvation diets, and intestine liners under type 2 where pancreas comes back on the job and system works better when excess glucose generation and nasty liver leaks arrested with drugs or application of GLP-1/GLP-5 hormones.

    That genes, auto-immune issues, environment and chemicals and other factors can influence the system but in my mind are further down the list. Liver leaks, hormone mis functioning and other system mis operation may have the issues buried in genes, environment etc.

    Lastly, the issue of insulin resistance is still not rationally dealt with and a total failure to accept that in a multi-storage location system as human body, controlled ignoring of Insulin in blood stream is a critical operation necessity to prevent the temporary sites being over loaded as some may be full and others still have room and/or exercising.

    End result is really an argument for energy balance in body and need to be managed by human directly to prevent saturation and shut down of insulin response and regulation of blood stream as there are no more temporary glucose storage sites on skeletal muscle sites to off load extra glucose from the blood stream and maintain regulation.

    This basically gets one to 3 factors:

    a) diet and glucose generation and need to size input energy fo actual burn and exercise.

    b) hearty exercise is needed to keep muscle sites temporary glucose sites off loaded regularly to keep blood stream regulated otherwise glucose backs up and rots out body.

    c) depending upon age, body destruction, gene changes, medicine intervention may be needed to stop excess liver leaks/glucose release and improper operation so as not to overwhelm a) and b) above.

    While we all want the single vampire silver bullit killing solution, factors suggest that this complex problem will need involved solutions wrapping around diet, exercise and medicine stratagies to get the complex human chemical processing machine and process put back on track.



  • Deb

    The blog post today on phthalates gives more evidence that there are many factors including the chemicals used in common household objects. I’m glad I’m chemically sensitive – no cosmetics, moisturizers, etc, etc, etc.

  • Nicole

    This is fascinating. Type II runs strong in both my parents families. Having the knowledge of my genes dictates my behavior. Knowing that I am at risk, changes my eating habits.

  • Andy

    Diet can make a huge difference. I am an RN and one of my case management pts went on Dr Esseltyn’s cardiac diet. He quicly was able to get off lantus and then had such symptoms of lows that he had to go off metformin. Wt is melting off and his bp/cardiac/cholesterol meds have also been decreased significantly. The issue is…can strict dietary changes be maintained by a diabetic.

  • John Thompson

    Let me tell you the story of two step brothers, same mother, different fathers. One is 66 the other is 58. Both grew up eating the same food, in the same house, both had and still have active lifestyles. One has a weight problem the other never has. One has diabetes, the other hasn’t never been sick. There is much more to this story and comparison. But to sum up, yeah, genes have a bunch to do with diabetes. No one, scientific or not, will convince me that my diesease has as much to do with my life style as the genes that I was given at birth. I also feel my tendancy toward obecity is gene related as I have fought and it all my life. I have lost as much as 100 pounds only to find it again and then some.

  • Jerame

    I am a 3rd generation diabetic. My grandfather had diabetes, was in the 300s and functioning fine in the nursing home. My mother, uncle, aunt, brother and cousins are diabetic. It’s definitely a genetic issue. I believe that the problem is there and is triggered by diet and lifestyle. I’ve been up and down with my A1C for 3 years and it is totally representative of how I eat and how active I am. However, no matter what I quit eating, it is still there. I could eat lettuce all day and still have higher than usual blood sugar. I’ve tried it. In my book, it’s no different than organ-specific cancers. Your body has a pre-disposition to some weakness. Once it’s triggered, your options are to deal manage it and keep it from progressing too rapidly. I know I will be on insulin eventually – maybe a year from now, maybe 10 years. It’s up to me on how I treat my body and if I want to “quit and give up” or if I want to fight it and not give in.

  • Dan Kashefska

    Often times we tend to blame genetics for our sicknesses such as diabetes, cancer, dementia, etc. I know that in my family we have a history of diabetes on my mother’s side and that is why my Drs’. Told me it was a genetic related issue.
    I produce enough insulin but my body has built up immunity to the insulin. I was diagnosed in 1994 of type 2 diabetes and have gone the gauntlet of medications, been counseled on eating, lost weight, all in vain in trying for a near normal A1C.
    In November of last year I started studying on an alternative medicine diet called the acid/alkaline diet. I learned that if I ate foods that cause an alkaline condition in my body my diabetes was easy to control. The body regulates it’s ph. to between 7.0 and 7.5 in order for me to stay alive.
    Studying books on this diet I learned what foods were alkaline forming and which ones were acid forming and that certain foods eaten together would make my blood sugar spike. I bought extra monitor strips and decided to test these theories as I learned them. I also check my urine and my saliva ph. every morning to see how my body is reacting. When I started this regime my ph was 5.8 on the urine and 6.4 on the saliva. This meant that my body had to get rid of a lot more acid than it could handle! I was also checking my sugars 8 times a day!
    To make a long story short, I started in November at 2000 Mg Metformin, and 26 units of Lantus a day. And now my urine ph is 7.0+ and my saliva is 7.2+ and I am taking 1000 or less Metformin and 6 units of Lantus a day and still having great blood sugar readings. My body I feel is (as the study said it would)lessening it’s insulin resistance because it is getting the proper foods! I still eat meat, veggies and lots of fruit, but NO processed meats and very very few processed grains.
    I have not had one glucose reading above what a normal person would have in over a month!
    Based on this, I think our western style diet is the main cause of diabetes, and to a much lesser degree the genetics. I know people that have no family history of diabetes that do have it also!
    This is not (as most dieticians say who do not understand this diet) a vegan diet!!!! I do NOT count carbs but keep track of my calories to make sure I maintain my current weight of 164lb. I am 6 Ft. tall and 71 yrs old.

  • Celeste

    I wish that people would get off Paula Deen’s back. They loved her recipes until they found out she had diabetes. That didn’t mean that she ate everything she cooked or baked. I don’t like fish but I cook it for people that want it.

  • sonia

    i believe some of us are predisposed to getting type 2 diabetes but can delay or even avoid it by not gaining excessive weight and exercising on a daily basis. when i was pregnant with all 3 of my kids gestational diabetes showed up once i had reached a certain weight. when i reached this same approximate weight a few years ago type 2 diabetes was diagnosed. i don’t believe my body was meant to handle the excessive weight. losing weight, taking metformin, and exercising daily now keeps my levels under control.

  • Bob Langley

    I am a Vietnam veteran who has developed Type 2 diabetes. The VA has determined that there is a relationship between exposure to Agent Orange and Type 2 diabetes. This would appear to indicate a third cause of diabetes, that being exposure to certain kinds of chemicals. Care to comment?

  • Bill Young

    I cured my T2 diabetes. When I was diagnosed, in Jan, 2009, my A1c was 7.6. The doctor wanted to put me on Metformin. I refused because I had seen my Dad die, horribly from T2 15 yrs earlier. He took his medications religiously. They did not stop the “complications” (euphemism!), they did not cure him, they did not save his life, he died from a massive heart attack as the majority of T2 diabetics do. In 4 months of my self discovered treatment, my A1c was 5.4 and has not gone higher than 5.6 since. My research showed that T2 was not a disease. It is a cluster of symptoms of various nutritional deficiencies, dehydration, acidosis and an overabundance of oxidants. Once I corrected those deficiencies with a predominantly vegetarian (alkaline) diet, augmented with Ionized, alkaline water, my body’s God given ability to heal itself kicked into high gear. Anyone can do it without, dangerous, ineffective, profit-making prescription drugs. And as far as falsely blaming genes, there is one big hole in the theory, genes cannot turn themselves on or off. They are triggered by external factors, such as food. Read the “Biology of Belief”, by Bruce Lipton for more info.

    • Valerie JM

      Metformin does work actually, but not if you continue to eat high carbs and high protein. My research showed that you can never be cured from diabetes. You always have to control it by eating properly as above.

  • Judith Volpe

    Although I believe diet and avoiding obesity are most important, I believe there is a heavy load of environmental toxins, such as BPA [don’t touch those cash register receipts, folks]contributing to insulin resistance and diabetes which is not being addressed. I study family histories and people with no family history known are becoming prediabetic/diabetic or having the onset long before their relatives. That being said if the genetic dice are heavily loaded in favor of it, diabetes will eventually come, except perhaps for the wheatgrass drinking, rigid raw foodist with a BMI under 19.

  • Betty Carr

    I grew up knowing that one day I would become a genetic type 2 diabetic. Almost everyone in my parents families did including my Mom and Dad. A few were overweight but most were not. Thanks to my Mother teaching me proper food choices early on I have never been overweight. I was cautioned by my Dr. when I was in my teens to always keep my weight down and I would likely be able to avoid diabeties until a later in my life. He was correct. I made a study about keeping a diabetic healthy in my teens and developed lots of interesting healthy food for my diabetic parents.
    I am now in my sixties and I am a type 2 diabetic. However I am very healthy because I keep up with all the latest information and take this desease very seriously. With proper diet my weight has always been good (5’3″ weight between 110 and 113lbs.) and I am able to control my blood sugar with meds as well. My A1C (three month average) is 6 (Canadian measurement) Meaning perfect.
    From my experiance and knowlege I can say without reservation that the concepts you have presented are all true. There are thoes who are genetically pre-disposed to becoming a diabetic. and those who allow their weight to go overboard. One possibly revealing way to find out which one you have is to bring your weight down to normal. If the diabetic situation goes away it means you are likely eating way to many calories and your body could not properly handle it. I say possibly because there are other factors that will influence becoming diabetic.
    I see so many very overweight people with the tell tale large girth around their middle. Every Dr. out there with patients in this condition should do a simple glucose fasting blood test and the A1C blood test. In fact if this describes anyone reading this, go to your Dr. and ask for these tests. It can save your life.
    The simple truth will always be there. If you are very overweight you are asking for trouble. If diabeties is in your family be aware that If one of your parents is a diabetic you have a 50% chance of developing it. If both have it the chances move to 75%. If you are overweight at any age, get it checked out. Even today in our enlightened society we still are what we eat.

    • Valerie JM

      An A1c of 6 is not perfect. A1c between 5.7-6.4 is considered high risk (in Canada)

  • David Spero RN

    Excellent comments as usual. I will address them in a follow-up piece next week.
    Certainly my title “Genes or Food” oversimplified the problem. It’s genes AND food, and stress, and physical activity (or lack of), and chemicals in our environment and in our food.

  • Jackie Kelley RN MS CDE

    Excellent synopis of the issues. Thank you for writing this article.