Does a Ketogenic Diet Help Diabetes or Make It Worse?

BY Michael Greger TIMEJuly 31, 2022 PRINT

Keto diets put to the test for diabetes reversal. The reason keto proponents claim they can “reverse” diabetes is that they can successfully wean type 2 diabetics off their insulin. 

Keto Diets and Blood Sugar

Ketogenic diets can certainly lower blood sugars, better than conventional diets—so much so, there is a keto product company that claims ketogenic diets can “reverse” diabetes. But they are confusing the symptom—high blood sugars—with the disease, which is carbohydrate intolerance. People with diabetes can’t properly handle carbohydrates, and this manifests as high blood sugars. Sure, if you stick to eating mostly fat, your blood sugars will stay low, but you may be actually making the underlying disease worse, at the same time.

We’ve known for nearly a century that if you put people on a ketogenic diet, their carbohydrate intolerance can skyrocket—within just two days. Here’s the blood sugar response of someone eating sugar after two days eating a high-carb diet. Here’s exposure to the same amount of sugar after a high-fat diet for two days. Their intolerance to carbohydrates skyrocketed on a high-fat diet.

One week on an 80 percent fat diet, and you can quintuple your blood sugar spike in reaction to the same carb load, compared to a week on a low-fat diet. Even a single day of excessive dietary fat intake can do it. If you’re going in for a diabetes test, having a fatty dinner the night before can adversely affect your results. One meal high in saturated fat can make the cause of diabetes—carbohydrate intolerance—worse within four hours.

Does Keto Make Diabetes Worse?

Now, with enough weight loss by any means—whether from cholera or bariatric surgery—type 2 diabetes can be reversed. But a keto diet for diabetes may not just be papering over the cracks, but actively throwing fuel on the fire.

I’ve been trying to think of a good metaphor. It’s easy to come up with things that just treat the symptoms without helping the underlying disease, like giving someone with pneumonia aspirin for their fever, instead of antibiotics. But a keto diet for diabetes is worse than that, because it may treat the symptoms while actively worsening the disease. So maybe it’s more like curing the fever by throwing that pneumonia patient out into a snow bank. Or maybe “curing” your amputated finger by amputating your hand. No more unsightly finger stub! One of the co-founders of masteringdiabetes.org suggested it’s like a CEO that makes their bad bottom line look better by just borrowing tons of new cash. The outward numbers look better, but on the inside, the company is just digging itself into a bigger hole.

Remember “The Club”? Maybe I just watched too much late-night TV growing up, but it’s a car anti-theft device that attaches to your steering wheel and locks it in place, so the steering column can only turn a few inches. Imagine you’re in a car at the top of a hill with the steering wheel locked. Then the car starts rolling down the hill. What do you do? Oh, did I mention there’s also something stuck under your brake pedal too? The keto-diet-equivalent-response to this situation is who cares if you’re barreling down into traffic with no brakes and a locked steering wheel. Just stick to really straight deserted roads without any stop signs or traffic lights. If you do that, problem solved! Yeah, the longer you go, the more speed you’ll pick up, and so if you should hit a dietary bump in the road, or start to veer off the path, the consequences could get more and more disastrous with time. But if you stick to the keto straight and narrow, you’ll be A-OK. In contrast, the non-keto response would be to just unlock the steering wheel and dislodge whatever’s under your brake. In other words, fix the underlying problem, instead of just whistling past (and then into) the graveyard.

The reason keto proponents claim they can “reverse” diabetes is that they can successfully wean type 2 diabetics off their insulin. That’s like faith healing someone out of the need for a wheelchair by making them lie in bed the rest of their life. No need for a wheelchair if you never move. Their carbohydrate intolerance isn’t gone; their diabetes isn’t gone. It could be as bad or even worse. Type 2 diabetes is reversed when you can wean people off insulin eating a normal diet like everyone else—then and only then do you not have diabetes anymore. A true diabetes reversal diet is practically the opposite of a ketogenic diet;  diabetics off their insulin within a matter of weeks, eating more than 300 grams of carbs a day.

Dangers Beyond Diabetes

The irony doesn’t stop there. One of the reasons diabetics suffer such nerve and artery damage is due to an inflammatory metabolic toxin known as methylglyoxal that forms at high blood sugar levels. Methylglyoxal is the most potent creator of advanced glycation end products, so-called AGEs, which are implicated in degenerative disease from Alzheimer’s disease and cataracts to kidney disease and strokes. You get AGEs in your body from two sources: eating them preformed in your diet, or making them internally from methylglyoxal if you have high blood sugar levels. On a keto diet, one would expect high exposure to the preformed AGEs, since they’re found concentrated in animal-derived foods high in fat and protein. But we would expect less internal new formation due to presumably low levels of methylglyoxal, given lower blood sugars not eating carbs. Dartmouth researchers were surprised to find more methylglyoxal, though. A few weeks on the Atkins diet led to a significant increase in methylglyoxal levels, and those in active ketosis did even worse—doubling the level of this glycotoxin in their bloodstream. It turns out high sugars may not be the only way to create this toxin.

One of the ketones you make on a ketogenic diet is acetone (known for its starring role in nail polish remover). Acetone does more than just make keto dieters fail breathalyzer tests and develop what’s been described as “rotten apple breath.” Acetone can oxidize in the blood to acetol, which may be a precursor for methylglyoxal. That may be why keto dieters can end up with levels of this glycotoxin as high as those with out-of-control diabetes, which can cause the nerve damage and blood vessel damage you see in diabetics. That’s another way keto dieters can end up with a heart attack. So, the irony of treating diabetes with a ketogenic diet may extend beyond just making the underlying diabetes worse, but by mimicking some of the disease’s dire consequences.

Michael Greger, MD, FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. He has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on “The Dr. Oz Show” and “The Colbert Report,” and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. This article was originally published on NutritionFacts.org
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