The work looked at what happened in people with prediabetes, a condition characterized by higher-than-normal blood sugar levels that put people at higher risk for diabetes, adopted a low-carb diet. Prediabetes may affect 96 million US adults.
However, the effects of a low-carb diet did not have the same result in white and black participants. The study found a low-carb diet was much more effective in lowering blood sugar in white participants compared to black ones.
Black people represented 59 percent of the study participants.
The randomized clinical trial – the gold standard in scientific research – enrolled 150 older adults with prediabetes. All were overweight (average BMI was 35), and nearly three-quarters were women.
Over six months, half were randomly assigned to a low-carb diet with frequent dietary counselling, while the others continued with their usual eating habits.
During the first three months, the low-carb group had to keep carbohydrate intake below 40 grams per day, which is roughly the amount found in an English muffin and apple. From the fourth month onwards, the limit increased to 60 grams daily.
The low-carb group was told to focus on eating non-starchy vegetables, fish, poultry, lean meat, eggs, olive oil, avocados, nuts, and seeds, Greek yogurt, low-carb milk, and small amounts of cheese. They were told to avoid fruits, other forms of dairy, legumes, beans, and grains.
The low-carb group lost an average of 13 pounds during the trial period. They also saw greater improvements in A1C and fasting blood glucose levels, which represented a 60 percent lower risk of developing diabetes within the next three years.
It is unclear, however, if the improved blood sugar resulted from the low-carb diet or the fat loss.
Adopting a diet where carbohydrates are kept this low is unsustainable in the long term. Instead, people should focus on making better nutritional decisions and dialling down bread, sweets, and starchy vegetables.
Focusing on weight loss and including more activity can also help promote lower blood sugar and reduce the risk of type-2 diabetes.