Diabetes experts have been arguing about the best diet for patients with type-2 diabetes for decades. Past and present studies now show that a diet low in carbs can help people with type 2 diabetes lose weight and control their blood sugar.
Conflicting dietary recommendations for people with diabetes can be confusing. Some experts emphasize reducing the amount of fat in diets designed for weight loss. Since many people with type 2 diabetes are also overweight, nutritionists have suggested they avoid fat to lose weight. However, if you eat less fat, you usually end up eating more carbohydrate. Is that a problem for people with diabetes?
Lowering Blood Sugar by Sticking with a Low-Carbohydrate Diet:
A new study in JAMA Network Open demonstrates that following a low-carbohydrate diet for six months can significantly lower hemoglobin A1c, or HbA1c (JAMA Network Open, Oct. 26, 2022). This blood marker is an indication of blood sugar control over several weeks and is considered a crucial metric.
Researchers recruited 150 adults 40 to 70 years old with HbA1c levels between 6.0% and 6.9%. That range put them between pre-diabetes and diabetes. None were taking medication to lower their blood sugar. The investigators randomly assigned participants to follow their usual diet or to adopt a diet low in carbs.
“The low-carbohydrate diet promoted was characterized by components thought to improve cardiometabolic health: unsaturated fat and protein, high-fiber foods, and minimal refined carbohydrates.”
For the first three months, participants got counseling to keep carbohydrate intake under 40 grams a day. For the next three months, the daily target was under 60 grams.
The researchers report that
“Compared with usual diet, the low-carbohydrate diet intervention also led to greater 6-month reductions in fasting plasma glucose, body weight, fasting insulin, and waist circumference.”
As a result of people in the low-carb group eating fewer calories and losing trimming their waistbands, the scientists could not state with certainty that the benefits were due exclusively to the diet low in carbs. Previous studies suggest this is plausible, however.
Fighting Diabetes with a Diet Low in Carbs:
An earlier study in JAMA Internal Medicine compared group medical visits for type 2 diabetes (JAMA Internal Medicine, Nov. 4, 2019). In the trial, which ran nearly a year, half the patients got standard care through group medical visits at the VA. At the same time, dietitians counseled the other half on a low-carbohydrate approach to weight loss. These patients also attended group medical visits for their standard medical care.
What Did the Study Show?
Both groups improved their HbA1c, a measure of blood sugar control. In addition, those following diets low in carbs lost more weight, used fewer diabetes medications and had fewer episodes of hypoglycemia. Hypoglycemia, in which blood sugar drops too low, can be a serious medical problem.
The authors conclude:
“The results from this study indicate that intensive WM [weight management] using a low-carbohydrate diet can be as effective for glycemic improvement as medication intensification in GMVs [group medical visits].”
Previous Support for a Diabetes Meal Plan That Is Low in Carbs:
This is not the first time we have written about research supporting a low-carb approach for people with diabetes. Although all the participants in this research had type 2 diabetes, even people with type 1 diabetes have reported better blood sugar control when they eat fewer carbs. Dr. Richard Bernstein, who had type 1 diabetes himself, was an advocate for this approach based on self-experimentation.
Moreover, an earlier study compared in-person, on-site group visits to web-based nutritional counseling to achieve ketosis (JMIR Diabetes, March 7, 2017). The individuals who adopted a diet low in carbs were able to lose weight, lower their HbA1c and discontinue some of their diabetes medicines.
A Conflicting Report:
On the other hand, a recent study from Scotland found that lower carbohydrate, higher fat diets were associated with elevated HbA1c values (European Journal of Nutrition, online Nov. 4, 2019). This was a survey rather than a clinical trial, so we don’t know what people were eating. Perhaps the quality of the diet with respect to micronutrients matters as much as whether it is low in carbs.
Researchers may not have established a best diet for diabetes beyond question. However, people who want to control their blood sugar might consider trying a low-carb approach.