Are low-carb diets better for people with type 2 diabetes?

This study compared the effects of two different diets in people with type 2 diabetes (T2D). It was determined that a low carbohydrate, high unsaturated fat and low saturated fat diet (LC) achieved the same weight loss and reductions in HbA1c (average blood glucose over the last 3 months) as a high carbohydrate/low fat diet (HC). It was also found that the LC diet reduced the need for diabetes medications and changes in blood glucose levels (glycemic variability) more than the HC diet. 

T2D may be associated with a high-calorie diet and lack of physical activity. Thus, lifestyle interventions are often useful. However, the most effective diet has not yet been decided. A high unrefined carbohydrate/low fat diet is usually recommended. Unrefined carbohydrates include brown rice, whole wheat, and oats. However, recent evidence suggests that reducing carbohydrates, and increasing protein and unsaturated fats in the diet may be better. The long-term effectiveness of these diets however, has not been well studied in people with T2D.

115 adults with T2D were recruited for this study. They were randomly divided into two groups. One group received the LC diet. The other received the HC diet. Saturated fats (such as those found in meat and dairy) were limited in both diets. Both diets contained the same total number of calories. All participants took part in an exercise program and were helped by a dietitian. They were followed up at 6 months, 1 year, and finally after 2 years.

61 participants completed the study. Participants from both groups had similar reasons for discontinuing the study.

Both groups achieved a similar amount of weight loss. The average weight loss at 2 years was 6.6 kg for the HC group and 6.8 kg for the LC group. Both groups had similar reductions in blood pressure, HbA1c, body fat, and fasting blood glucose (glucose levels after a period without food or drink). Similar reductions in bad cholesterol (LDL cholesterol) were seen in both groups. Good cholesterol (HDL cholesterol) was maintained in the LC group, but slightly reduced in the HC group.

Participants in the LC group had greater reductions in diabetes medication use. Greater reductions in blood glucose variability and triglyceride levels (another type of fat found in the blood) were also seen in the LC group.

The study concluded that both diets achieved similar weight loss and HbA1c reductions. However, the LC diet led to greater reductions in medication use, glucose variability, and triglycerides. The LC diet also improved cholesterol levels.

This study only examined a small number of people, just over half of which completed the study. The majority of participants were Caucasian, and all were overweight or obese. Thus the results of this study may not apply equally to all people with T2D.

Discuss the benefits of different diets with your physician.