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Home » Does sugar cause diabetes? The answer is probably no

Does sugar cause diabetes? The answer is probably no

One of the most pernicious myths about food is that somehow eating sugar causes diabetes. I even was watching a TV comedy where the character was going to dig into a cake, and another character says, “I’m getting diabetes (see Note 1) just by watching all of that sugar.”

No. Sugar is not linked directly to diabetes, so go ahead, eat that delicious, rich, sweet chocolate birthday cake. However (see Note 2), there might be some very indirect links between eating too much sugar and diabetes, but not as a result of eating sugar alone.

Moreover, another myth is that all diabetes is the same. They’re not. Let’s take a look at diabetes and the lack of direct evidence that sugar causes diabetes.

All about diabetes

We’re going to dive into some medical science here so that everyone is on the same page about diabetes since there seems to be so much misinformation out there. I tried to summarize books on diabetes into a few paragraphs, so I hope this is clear to the reader.

Blood sugar regulation

Lots of science here, but diabetes is a complex disease. Oversimplifying it can make some people think that it’s simple to treat or even cure. I need to disabuse the reader of that belief if you have it.

The basic power source of our body is glucose, which is produced from almost anything we eat (carbohydrates, proteins, sugars, and fats). It is usually tightly regulated by the body, and when you have excess glucose in the blood, it is taken out of the blood and stored–but when the blood glucose drops, it is then released from storage to be used for energy.

The key hormone, insulin, which regulates the level of glucose in the body is released by the Beta cells of the Islets of Langerhans in the pancreas when blood sugar goes up–insulin induces storage cells to remove and store glucose from the blood. In a complex interaction, the hormone glucagon, which is produced by other cells in the pancreas when the blood glucose level is too low, then induces the release of that stored glucose.

This shows, once again, how complex living systems are, and simple explanations about the physiological processes in humans are laughable and should be dismissed. Moreover, glucose control in humans is a fascinating physiological system, and, remarkably, it works so well in 99% of people.

Type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that is characterized by autoreactive T lymphocytes (T-cells) that destroy pancreatic islet cells, which are critical to glucose metabolism by producing insulin. These lymphocytes mistakenly attack the islet cells as if they were a foreign body, as they do with a viral or bacterial infection.

In addition, regulatory T-cells (which are often called Tregs) modulate the immune system and would normally reduce the effect of an autoimmune attack. Tregs act like brakes that normally prevent mistaken attacks, like on the pancreatic islet cells, without affecting the whole immune system. A branch of diabetes research has suggested that abnormal Tregs could be the key to finding treatments to reverse type 1 diabetes.

Once the pancreatic islet cells are damaged, they no longer produce hormones, especially insulin, that help regulate the levels of blood glucose. Without insulin, the blood glucose levels increase rapidly leading to long-term damage to eyesight, kidneys, limbs, heart, and other organs.

Type 1 diabetes can be deadly if uncontrolled blood sugar leads to a life-threatening condition called diabetic ketoacidosis. Without regular insulin injections, a patient has little chance of living beyond a short period, and even then it could be a horrifically painful demise.

It is not known what causes this autoimmune disease, although there is strong evidence that genetics is the most important factor. However, other things may be implicated, like vaccine-preventable diseases, which could be important co-factors in the development of the disease. Just to be clear, vaccines are not linked to type 1 diabetes.

Currently, there are no known cures for type 1 diabetes. The only treatment for the disease is regular injections of human insulin, manufactured from genetically engineered E. coli cultures. In addition, careful diet and lifestyle management help regulate blood glucose levels, although it cannot replace insulin injections. However, there may be a vaccine that may reverse T1DM, but it’s early in the clinical research, and we may know if it works by the mid-2020s.

Before the wide availability of insulin in the 1920s (usually pig insulin whose structure is similar to human insulin, but still caused a lot of allergic reactions), children simply died of the disease. Nothing could be done.

Finally, T1DM should not be confused with two other types of diabetes, one called latent autoimmune diabetes of adults (sometimes called LADA or Type 1.5 diabetes), but has no practical difference with T1DM except the age of the commencement of symptoms. Instead of showing symptoms as a child, it appears in late adulthood, typically 30s and early 40s. Like typical Type 1 diabetes, the only treatment for LADA is regular insulin injections.

Type 2 diabetes mellitus

The other important form of diabetes is Type 2 diabetes (T2D), which is probably caused by a combination of genetics, obesity, eating behavior, and several other lifestyle factors. Usually, in T2D, the pancreas produces sufficient insulin, but the body’s cells and organs become “resistant” to the insulin, meaning that they ignore the signal to store glucose, and thus the blood glucose remains high.

Oral medications and behavioral changes, such as improved diet and exercise, can often help manage if not reverse T2D. Eventually, a person with chronic T2D may also have to take insulin.

Type 1 and Type 2 diabetes are truly two different kinds of diseases with one common symptom, excess blood glucose levels.

There is a form of diabetes called gestational diabetes, which results in high blood sugar in pregnant women, usually in the third trimester. Unfortunately, it is not well understood what causes it, and if it remains untreated, it could lead to other types of diabetes.

T2D is the most prevalent form, making up about 90-95% of all diabetes, and is a type of metabolic disease that can be treated without medication through weight loss, dietary modification, and exercise. However, since all of those treatments are hard work, oral diabetes medications and insulin are eventually prescribed for the treatment of the disease, when the blood glucose remains out of control.

There is a strong correlation between type 2 diabetes and obesity, although there are other risk factors like genetics and sleep habits. Across the world, type 2 diabetes has skyrocketed from 30 million in 1985 to 285 million in 2010. In the USA, 8.3% of the population has diabetes, which costs the country about $116 billion in direct medical spending.

Sugar causes diabetes myth

First, scientists agree that type 1 diabetes is considered an autoimmune disease leading to the destruction of the insulin-producing cells in the pancreas. Sugar does not cause nor does it trigger type 1 diabetes.

Second, it is also well understood that dietary sugar does not cause type 2 diabetes. The Joslin Diabetes Center calls it a “myth” that sugar causes diabetes. Similarly, Diabetes UK states that “we know sugar doesn’t directly cause Type 2 diabetes.” The American Diabetes Association considers “eating sugar causes diabetes” as a myth.

However, as I wrote above, lifestyle factors have a considerable impact on the risk of type 2 diabetes. One of those factors is obesity – one of the biggest factors leading to it can be a diet high in calories from any source, including sugar. There is research that sugary drinks can lead to type 2 diabetes (see Note 3) – again, not directly, but through an increase in weight. The American Diabetes Association does recommend people should avoid intake of sugar-sweetened beverages to help prevent diabetes, not because of the sugar itself, but because of the risk of obesity.

Actually, from a physiological standpoint, fat-rich diets raise blood sugar more than sugar-rich diets (and just to be clear, fat-rich diets do not cause diabetes itself). Fats may contribute to insulin resistance, which is a primary factor in type 2 diabetes. Of course, most processed foods have too much sugar and fats so they are double trouble for obesity and diabetes.

Furthermore, dietary carbohydrates (a long chain of sugar molecules) are not linked to developing type 2 diabetes. I can’t stress this enough – excess carbohydrates and sugars over time may lead to diabetes, but it’s part of the “lifestyle” choices that lead to obesity which, in conjunction with genetic predisposition, cause type 2 diabetes.

There is pretty solid evidence that there are actual benefits of switching from low- to high-carbohydrate diets for diabetes. Dr. Walter Kempner, in the 1950s, was able to reverse type 2 diabetes and vascular disease with a diet of white rice, fruit juice, fruits, and white sugar with no cholesterol or salt. I would not advocate this diet for anyone, but it does show that the “blame” for type 2 diabetes is very complex, and it’s not just sugar and carbs. And there is still good evidence 50 years later that this strange diet may help reverse type 2 diabetes, and it is still used effectively.


This is easy – it is a myth to claim that sugar causes diabetes, except in a most indirect way by contributing to obesity, which is known to be linked to type 2 diabetes. It does not directly cause either type 1 or type 2 diabetes.

There are so many myths about diabetes. I’m glad we could demolish this one. Don’t feel guilty about that one slice of chocolate cake.


  1. It’s pronounced dye-A-bee-teez. Not dye-a-bee-tus.
  2. Some people don’t get this about science – it’s not absolute. Of course, many people think that’s a “weakness” of science, but it’s not. All conclusions in science are provisional – it’s all about the evidence.
  3. This study, among many, debunks the myth that artificial sweeteners are linked to diabetes or obesity. Confounding factors in previous studies seem to imply a link, but once those were identified and accounted for in future studies, there was no link.


Michael Simpson
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