Low-Carb Diets Improve Blood Glucose Levels

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A recent study suggests that diets low in carbohydrates can rapidly suppress elevated A1C levels back to a healthy range in people who are pre-diabetic.

The study was published in October 2022 on JAMA Network Open.

While Dr. Giulio Romeo, associate medical director of the adult diabetes section at the Harvard-affiliated Joslin Diabetes Center, questioned whether low-carb diets are sustainable, he conceded the approach could be effective.

“Clearly, this study shows that a low-carb — and really, a borderline very-low-carb — diet is effective in reducing A1C levels, which are a measure of blood sugar during the previous three months,” said Romeo.

Pre-diabetic individuals have above-average blood sugar levels, a potential precursor to full-blown diabetes. The American Diabetes Association reported in 2021 that over a third of adults in Texas are pre-diabetic.

Researchers worked with 150 older adults over six months. All were overweight, with an average BMI of 35, and had untreated pre-diabetes or non-severe diabetes.

Participants were randomly divided into two groups. The first group was fed a low-carb diet and given access to regular dietary counseling. The second group consumed their standard diet.

The low-carb group ate a maximum of 40 grams of carbohydrates per day for the first three months, equivalent to the carbs present in one apple. For the remaining three months, the low-carb cohort was allotted up to 60 grams of carbs per day.

The carb-capped group was encouraged to consume protein-heavy meals and healthy fats, like fish, olive oil, eggs, and nuts. They were also advised to avoid beans, grains, and fruit to limit their carbohydrate intake.

Blood testing was conducted twice during the trial, at three and six months following the start of the diet. The low-carb group exhibited greater improvements in A1C and blood glucose levels at the six-month test compared to the higher-carb group.

The gains were substantial, correlating to an estimated 60% lower chance of developing diabetes over the coming three years. The low-carb participants also lost an average of 13 pounds over the half-year trial.

Unfortunately, the researchers could not conclusively say that the low-carb diet led to improved blood sugar management. It is instead possible, according to Dr. Romeo, that weight loss was the primary factor in improving A1C levels since losing fat helps reduce insulin resistance.

Still, the low-carb diet could be indirectly responsible. All else being equal, lower carbohydrate meals are thought to be more satiating, which can lead to less overconsumption.

This is part of the reason the keto diet — which prioritizes fat as an energy source — is so popular. Thus, it could have been a reduction in calories — bolstered by consuming a higher proportion of satiating protein and fat — that led to the weight loss, ultimately improving blood sugar regulation.

The study’s conclusions were also limited because the low-carb group was given access to dietary counseling, which may have helped them on their weight loss journey.

Regardless, Dr. Romeo said cutting back carbs, even a bit, can be beneficial.

“The fairly large carbohydrate intake we’ve all become accustomed to — breads, sweets, starchy vegetables — can be dialed down a bit,” he said. “Not only can that reduce the risk of diabetes, but it also may help weight loss.”

Obesity, a leading contributor to the development of Type 2 diabetes, has been on the rise across the country, even in the Dallas-Fort Worth area, which was recently ranked as the 27th most obese and overweight metro area in the United States, as previously reported in The Dallas Express.

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  1. ThisGuyisTom

    Good article.
    The body’s cells (mitochondria) get energy from one of two sources. Sugars (carbs) or lipids (oil). If sugars are not available, then the cells get in the habit of burning oil for energy.

    I often take a supplement (a protein) called Acetyl-Carnitine. It helps with the cell’s ability to use lipids (oils) as a fuel.
    It also helps with mental acuity. People often report that their energy levels are higher at work when they are physically active.
    Phosphatidylserine and Phosphatidylcholine are fatty substances called a phospholipids which help with brain and nervous system activity. Lecithin contains phospholipids. Acetyl-Carnitine helps process those lipids. Carnitine benefits the heart and other body functions.

    • ThisGuyisTom

      I should note that many experts are pointing out that Americans are consuming too many plant oils.
      Historically, mankind has never consumed this quantity.

      Dr. Chris Knobbe is an ophthalmologist and Associate Clinical Professor Emeritus via University of Texas Southwestern Medical Center.
      He has done some great research on the topic.


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