Top 7 Myths About the Cause of Type 2 Diabetes Debunked
- Brainz Magazine
- Jan 3
- 8 min read
Dr. Michael Donaldson is a nutrition researcher and health coach specializing in type 2 diabetes reversal. As founder of End Diabetes Now and Research Director at Hallelujah Diet, he empowers people to transform their health through evidence-based, plant-centered nutrition.
Type 2 diabetes is a raging epidemic. It is sweeping up more victims each year. The CDC says that about 19 percent of adults (or about 1 in 5) aged 45-64 in the USA have type 2 diabetes. And it increases to almost 1 in 3 (29%) among adults aged 65 or older. There are about 38 million people living with type 2 diabetes in the USA. To maintain true wealth in this great country, we need to overcome diabetes.
But to overcome type 2 diabetes, we need to understand precisely what is causing it. There's a lot of confusion about its exact root cause. In this article, I will present seven theories on the causes of type 2 diabetes and scientific evidence to the contrary.
Is type 2 diabetes caused by carbohydrates?
One of the most popular theories is that high blood sugar results from excessive sugar and carbohydrate intake. The thinking goes that high blood sugar comes from carbohydrates in the diet. However, it's not quite that simple.
In 1958, Dr. Kempner reported on 100 cases of diabetes treated with a rice and fruit diet. The rice diet was very restricted and inadequate in many ways. The caloric intake was 95% carbohydrate, 3-4% protein, and maybe 2% fat. Quite extreme. If diabetes were caused by carbohydrates, then this diet would not work at all.
Instead, they found that diabetes improved in many people using the rice diet under Dr. Kempner's care, and diabetic retinopathy improved as well, with published images of eye scans demonstrating this.
Of the 100 patients reported, 72 were taking insulin. Nine people had to increase their insulin, 21 had no change in their insulin, and 42 decreased their insulin requirement using Kempner’s rice diet, including 18 people who were able to discontinue insulin completely.
Clearly, type 2 diabetes is not caused by carbohydrates. That is all these people ate while reversing their disease.
I will give you one more example. Anderson and Ward worked in a metabolic ward in the 1970s, where they could track people's body weight and provide them with exactly the amount of calories needed to maintain it. They used a high-carbohydrate, high-fiber diet (HCF) in their work with diabetes.
First, they gave people a controlled diet for seven days. Then people adopted the high-carbohydrate, high-fiber diet (HCF). The average insulin dose was reduced from 26 units per day on the control diet to 11 units on the HCF diet within a matter of days. Insulin therapy was discontinued in 9 patients who had previously received 15 to 20 units per day.
Is type 2 diabetes caused by seed oils?
Seed oils have been controversial online, with many influencers claiming they are the root cause of many of our health maladies. However, the scientific record on polyunsaturated fats (PUFAs) proves otherwise.
In a 2022 meta-analysis of 25 articles, including 54,000 patients, Hu and colleagues found that total PUFA intake was not associated with type 2 diabetes. Linoleic acid, in particular, slightly decreased the risk of type 2 diabetes.
Using the EPIC-Potsdam cohort, Schulze’s research team conducted a nested case-cohort study with 1,084 participants, 536 participants with type 2 diabetes matched with participants without type 2 diabetes. They also found that plasma linoleic acid was associated with a slightly lower risk of type 2 diabetes. Also, arachidonic acid, derived from the metabolism of linoleic acid, was not associated with a higher risk of type 2 diabetes.
A study of 16,000 adults in the USA, from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2020, reported monounsaturated and polyunsaturated fatty acids and their association with prediabetes and type 2 diabetes risk. They found that those people with the highest tertile of PUFAs had a 49% and 68% lower risk of developing prediabetes or type 2 diabetes, respectively.
Is type 2 diabetes caused by too many animal products?
Another popular theory is that animal products cause type 2 diabetes. Neil Barnard and co-workers put this to the test in a 74-week randomized controlled clinical trial, comparing a low-fat vegan diet to a conventional diabetes diet.
Both diets caused sustained reduction in weight and glycemic control, with slightly better results in the vegan group. In the short-term analysis of the trial, 43% of the vegan group (21 of 49) and 26% of the ADA control group reduced their diabetes medications. The results were better with the vegan diet, but no participant in either group reported remission of type 2 diabetes.
So, if the cause of type 2 diabetes is animal products, this study would have had much better results after eliminating animal products for more than a year. The next citation below also proves this point and more.
Is type 2 diabetes caused by ultra-processed foods?
A strong case can be made for the contribution of ultra-processed foods to the cause of type 2 diabetes. They are linked with higher rates of cancer and increased risk of all-cause mortality. Still, if a whole-foods plant-based diet doesn’t get the best results, then ultra-processed foods are not the root cause of type 2 diabetes.
In a 24-week intervention study in the Marshall Islands, a culturally adapted, whole-foods plant-based diet was compared to standard medical care in the intervention group. For those who started with an HbA1c less than 9%, 63% reduced their glucose-lowering medications, and 23% of them achieved remission of their type 2 diabetes.
These are good results, but not the best.
Another kind of proof would be a study where people reversed type 2 diabetes and still kept eating ultra-processed foods. This would suggest that the cause is not ultra-processed foods.
In the DiRECT study led by Roy Taylor, the intervention group used a liquid total diet replacement for 12 to 20 weeks to lose weight and reverse their diabetes. In the DiRECT study, 68 of 129 people (45%) achieved remission in the first year, and 53 achieved remission in the second year. This is about double the remission rate of the whole-foods, plant-based diet used in the Marshall Islands.
However, for those who lost more weight, the results were even better. 57% of the participants (16 of 28) who lost 10 to 15 kg achieved remission, and 86% of the participants (31 of 36) who lost more than 15 kg achieved remission in the first year of the study, all while using ultra-processed meal replacement shakes.
Is type 2 diabetes caused by high fructose corn syrup?
Can you reverse type 2 diabetes and still eat products that contain high fructose corn syrup (HFCS)? Possibly. And does eliminating high fructose corn syrup reverse type 2 diabetes? No, it does not. That thinking is too simplistic.
For evidence, we can refer to the whole-foods plant-based diet intervention in the Marshall Islands mentioned above. They certainly eliminated high-fructose corn syrup and achieved good results, but not the best.
It isn’t that HFCS is not a contributor to type 2 diabetes. Fructose has a unique ability to contribute to fat accumulation in the liver, giving rise to non-alcoholic fatty liver disease.
In this 2022 study by Sigala and co-workers from UC Davis, the research group conducted a randomized controlled trial in which participants consumed three sugar-sweetened beverages per day containing 0%, 10%, 17.5%, or 25% of their daily energy requirements from high-fructose corn syrup. They measured liver fat with a very sensitive MRI scan.
They found a very direct linear dose-response relationship between liver fat and consumption of high-fructose corn syrup in sugar-sweetened beverages. The conclusion is that there's a direct dose-response increase in hepatic lipid content and a dose-dependent decrease in insulin sensitivity in young men and women when they consumed 10, 17.5, or 25% of their energy each day for two weeks as high-fructose corn syrup sweetened.
So, I would admit that high fructose corn syrup (HFCS) is a strong contributor to type 2 diabetes. But eliminating it alone will not have a dramatic effect without also losing body weight.
Is type 2 diabetes caused by eating too much fat?
The low-fat diet concept has fallen out of favor at this point. But how do we know that type 2 diabetes is not caused by eating too much fat?
For evidence, let’s consider dietary interventions using a ketogenic diet, which is low in carbohydrates, moderate in protein, and high in fats.
In this 2022 study by Christopher Gardner and co-workers at Stanford University, two low-carbohydrate diets were compared. One of them was a well-formulated ketogenic diet that excluded added sugars and refined grains, legumes, fruits, and intact whole grains, but included non-starchy vegetables. The second diet, called the Mediterranean Plus diet, likewise avoided added sugars and refined grains, as did the ketogenic diet, but also included legumes, fruits, and intact whole grains. The 33 participants experienced similar weight loss using either diet.
The point of citing this study is that a low-carbohydrate diet that includes substantial amounts of dietary fat can lead to weight loss and improved glycemic control simultaneously. So, type 2 diabetes is not caused by eating too much fat.
Is type 2 diabetes caused by being obese?
It is true that type 2 diabetes is strongly associated with obesity. And with increasing obesity, the probability of having diabetes increases greatly. Nevertheless, there are people in the normal range of body mass index (BMI) who also have type 2 diabetes. Also, most obese people do not have type 2 diabetes.
In a 2007 analysis of national surveys conducted around 2000, Bays and colleagues examined the distribution of BMI and the incidence of diabetes. In two different nationally representative samples, they found the prevalence of diabetes was 12% and 17% for people of normal BMI. Twenty years later, the CDC reports that about 10% of people with type 2 diabetes are of normal BMI.
This 2007 analysis also pointed out that the prevalence of diabetes is only 25-30% among those who are obese, which means that 70-75% of obese people do not have type 2 diabetes. There is a relationship between obesity and type 2 diabetes, but it is not an absolute.
If not these, then what causes type 2 diabetes?
We have now eliminated the usual suspects for the cause of type 2 diabetes. So what’s left?
The cause of type 2 diabetes is that you are too fat for you.
The Personal Fat Threshold is key to understanding what it means to be "too fat for you." It appears that each person has a threshold of fat content in their body, especially in their liver and pancreas, below which metabolic activity runs normally.
When fat accumulates excessively in the liver and pancreas, the liver does not function properly and does not respond to insulin signals from the pancreas. And the beta cells in the pancreas become ineffective in producing insulin.
So, there is too much of you. You're too fat for your own body if you have type 2 diabetes. This is an unpleasant truth, perhaps, but one that also brings freedom. When you know the true cause of diabetes, you can focus your attention on exactly what you need to do to reverse your type 2 diabetes. And this is good news.
You know that you do not have to be afraid of seed oils, carbohydrates, ultra-processed foods, high-fructose corn syrup, animal products, or any other demonized food group. Eliminating any single factor mentioned above will not reverse a person's diabetes.
Now you know that you have to become a smaller person. You need to lose weight. The work by Roy Taylor and colleagues indicates that about 15 kilograms of weight loss is generally necessary to reverse type 2 diabetes. This allows the liver and pancreas to function correctly. And then all you have to do is maintain this body size, and you will keep diabetes away for good.
Read more from Michael Donaldson
Michael Donaldson, Nutrition Researcher & Health Coach
Dr. Michael Donaldson, Ph.D., is a leading voice in plant-based nutrition and lifestyle transformation. With a doctorate from Cornell University and more than two decades of research at Hallelujah Diet, he has helped thousands understand how food can restore health and vitality. Through his coaching platform End Diabetes Now, he guides clients in reversing type 2 diabetes naturally and sustainably. A scientist, entrepreneur, and educator, Dr. Donaldson also founded True Wealth Health Products and formulated Ora-Shield, an organic oral-care blend. His work bridges science, faith, and practical wisdom to help people achieve lasting wellness and purpose.
