Higher Fat, Lower Glucose?

Fat has long been demonized in medical and dietary circles, for a variety of reasons. For decades, as a recent Time magazine cover story pointed out, saturated fat in particular has been singled out as a cause of heart disease — an association that some dietary experts believe has been exaggerated. Trans fats — created in the process of partially hydrogenating oils, resulting in an artificial fat that is often used as shortening, for frying, or as a food additive — has been identified as detrimental to cardiovascular health and should be avoided entirely. At the same time, all fat has been portrayed as potentially harmful because it is a concentrated source of calories: 9 calories per gram, compared with 4 calories per gram of protein or carbohydrate. Due to the health benefits of weight control, people with diabetes — Type 2 diabetes in particular — are often advised to limit their fat intake, in addition to watching their intake of refined sources of carbohydrate. A new study, however, adds to a growing body of evidence that dietary fat may not be the enemy of people with diabetes.


The study, published earlier this month in the journal Diabetes Care, examined the effects of canola oil in the diets of 141 people with Type 2 diabetes, all of whom took oral diabetes drugs. Some participants were assigned to the study group, in which case they were given a canola oil–enriched bread supplement and counseled on how to follow a low–glycemic load diet. All other participants were assigned to the control group, in which case they were counseled on following a whole grain–based diet and given a whole-wheat bread supplement. According to an article on the study at MedPage Today, after three months, participants in the canola oil group had experienced an average drop in HbA1c (a long-term measure of blood glucose control) of 0.47%, compared with a drop of 0.31% in the whole-wheat group. Members of the canola oil group also lowered their Framingham risk score (a measure of cardiovascular risk based on cholesterol levels and blood pressure, among other factors) by 0.6 percentage points more than the whole-wheat group.

Other studies have also found glucose-lowering or diabetes-fighting benefits from including certain kinds of fat in the diet. Earlier this year, a Spanish study found that among adults at high risk for cardiovascular disease, following an olive oil–rich Mediterranean-style diet reduced the chances of developing Type 2 diabetes by around 40%, compared with following a low-fat diet. Another study from earlier this year found that among overweight or obese people with Type 2 diabetes, eating a large breakfast rich in fat and protein lowered HbA1c by an astounding average of 4.62%, compared with 1.46% in a small-breakfast control group. But there is opposing evidence when it comes to fat and glucose control: A 2006 study found that a low-fat vegan diet lowered HbA1c by 0.96% in a group of participants with Type 2 diabetes, compared with 0.56% in a group following the dietary recommendations of the American Diabetes Association.

What’s your take on the relationship between dietary fat and blood glucose control — have you noticed a pattern in your own diet? If you’ve found fat to be helpful in controlling blood glucose levels, has it been helpful (or harmful) in other areas, such as weight control or managing cholesterol levels? Have you found nutrients other than fat, such as protein or fiber, to be helpful in maintaining blood glucose control? Leave a comment below!

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  • James Flinn

    Most interesting. I am not overweight, have Type 2 and do watch my diet a lot – fish at least 4 times a week, lean chicken, little beef and lots of vegetables sply for cooking and do use canola and olive oil sparingly for cooking. I do have a penchant for cheese and often have a few pieces of cheese ($5 to 30/lb kinds) after dinner. Would be interested in the risk of eating cheese made from cow, goat, sheep, and other milk. Thanks for the info on olive and canola.

  • R Liles

    I have tracked and charted my fasting blood glucose for the last five years and have found only two things that have had any measurable effect (and I’ve tried quite a few things). 1. A very low fat diet (20-30g fat per day) on the Barnard diet; 2. Addition of glipizide.
    The low fat diet reduced fasting glucose from an average of 150 down to 110 following the diet for one year. A diet that low in fat is difficult to do. I stopped and the fasting bg went back up in a few months.
    Glipizide lowered the fasting bg to 110 in one month but after 3 months it no longer worked.

    I am a normal weight Type 2 (diagnosed ten years ago) on metformin with genetic iron overload.

  • JohnC

    Would have been more interesting to have a group with no grains (bread) at all in the equation.

    Really appreciated the feature article on low carb diets this week — very fairly written!

  • Ferne

    I have read several articles from other sources that say Canola oil is not healthy. There are so many different ideas out there so who is to say which one is right? It gets confusing when so many dieticians and other experts have so many ideas and how are we to know which is the healthiest?

  • Dan Bergen

    First off I am not advocating this for anyone else. Everyone must find what works for them.

    I was diagnosed with type 2 in 2012, with an A1C of 7.4. At the time I was 252 lbs., at 6′ 4″. I also had high cholesterol mainly driven by elevated LDL, as well as high triglycerides. I have some heart disease. I was on both cholesterol and heart medicine. My doctor prescribed Metformin, and I began taking it. I also began reading information in books and the internet.

    A book by Taub struck a chord, as did the thought that if glucose (sugar) consumption was the culprit, then stop eating it was the solution. In a nutshell I became convinced that in a very low sugar/carb diet, that included high fat, moderate protein one could control blood sugars, and positively impact cholesterol. I began that diet, consuming approx. 20mg of carbs, or less, per day. I eat a lot of meat, chicken, fish, cheeses, eggs,nuts and low carb veggies, now and then low carb fruit.

    My next A1C was 5.8, and my doctor took me off of metformin. Over the next year my weight dropped from 252 to 203, without watching calories. I did start walking, but I am somewhat physically limited with a bad back and foot neuropathy. As predicted by Taub, my high fat, very low carb diet resulted in a substantial drop in triglycerides and LDL, an increase in HDL which today is 99. Two years later I am still 203, my last A1C was 6, and my lipids are good.

    My doctors and the ADA dietician were highly skeptical when I told them of what I was doing. The dietician did admit that people had good results eating this way, but it was sustainable for only short periods of time. I’ve been doing it for two years, no plan to stop. It does take will power and planning, especially when eating at parties and dinners. Restaurants are no problem.