Type Two Diabetes: Sugar or Fat?

There is widespread agreement among researchers who study type two diabetes that a chief driver of the disease is resistance to insulin. People who suffer from insulin resistance, diabetic or not, generally have higher blood sugars and are also at greater risk for other related diseases like cardiovascular disease.

In the film, “What the Health,” Dr. Neal Barnard gives an explanation of his understanding of what drives type two diabetes:

“Diabetes is not and never was caused by eating a high carbohydrate diet, and it’s not caused by eating sugar. The cause of diabetes is a diet that builds up the amount of fat into the blood. I’m talking about a typical meat-based, animal-based diet. You can look into the muscle cells of the human body and you find that they’re building up tiny particles of fat that’s causing insulin resistance. What that means is the sugar that is naturally from the foods that you are eating can’t get into the cells where it belongs. It builds up in the blood and that’s diabetes.”

There’s a lot there that I agree with. But, I have a problem with the final picture.

This idea that fat in the muscles (intramyocellular lipid) blocks sugar from entering muscles, creating a sugary traffic jam in the circulation, doesn’t really fly. If it were true, type one diabetics, who lack all insulin, would be unable to move sugar into their muscles and would have a great deal of trouble with muscle function.

There are lots of problems in type one diabetes, but inability for muscles to get sugar is not one of them. That’s because there are ways for muscle cells to get sugar that don’t rely on insulin at all. So your muscles can be resistant to, or completely lack insulin and they will still be able to get energy from sugar. In fact, as glucose levels in the blood stream rise, the movement of sugar into cells can happen without insulin or transporters. The glucose simply moves from a higher concentration in the blood to the lower concentration in the cell, in the same way oxygen does.

So this picture of type two diabetes as a log jam of sugar blocked by insulin resistance from its home inside the cell can’t be the whole picture, and I believe it isn’t.

Let me be clear, Dr. Barnard is correct in all the particulars. Foods that are fatty do cause insulin resistance, carbohydrate is not the primary cause of type two diabetes and fat buildup in muscle cells does cause them to become resistant to insulin.

But a complete picture of what is going on in type two diabetes really needs to focus on the liver. The liver has a very important metabolic job. It makes sure that when there is no food present, blood sugar doesn’t drop below levels that would be dangerous.

Imagine the liver then, as a faucet that drops sugar into the blood stream. Insulin, when working properly, turns the faucet nearly off. This is why insulin can be deadly.

If you give yourself insulin and fail to eat, the sugar from the food will not be present, but because the insulin is present, the liver doesn’t know to turn back on production of sugar and sugar levels can drop to lethal lows.

However, when insulin resistance is created by fatty, meaty diets, the liver’s faucet becomes much harder to modulate and turns more slowly. Glucose continues to get made in the liver. This manufactured sugar joins the sugar in the bloodstream from the meal, resulting in much higher total blood sugar. The muscle cell is not the focus of the problem, because the bigger issue is over-production of liver-derived sugar.

The most commonly used medication for type two diabetes, metformin, works by blocking the liver’s ability to make large amounts of sugar, but has very little or no action in the muscles.

To reiterate, sugar is not good for you, nor is it a health food. But it is not the primary cause of diabetes. Type two diabetes is caused by insulin resistance. To illustrate this, a researcher in 1927 named Shirley Sweeney did experiments on medical students. One group ate foods like cotton candy and maple syrup, another fasted, a third ate a high protein diet and the last ate a diet high in bacon grease, shortening and butter.

Here’s the glucose tolerance test of the ones who ate the cotton candy and maple syrup:

Here’s the glucose tolerance test of the ones who at the bacon grease, shortening and butter:

The difference is clear. The high fat diet induced frank diabetes with scores that would confirm a diagnosis of type two diabetes even today. The high sugar diet showed nearly no increase in glucose levels at all.

Although fat is the true culprit, please don’t eat a diet high in sugar. Sugar has all kinds of negatives. Instead, choose healthy, complex carbohydrates that digest slowly and carry along with them other important nutrients. Eat corn, beans, squash, rice, quinoa and lentils. Spice them up, mix them with fruit and vegetables, and enjoy them.

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