A variety of dietary patterns can improve body weight and average blood sugar levels in people living with type 2 diabetes

Bonekamp NE, van Damme I, Geleijnse JM, et al. Effect of dietary patterns on cardiovascular risk factors in people with type 2 diabetes. A systematic review and network meta-analysis Diabetes Res Clin Pract. 2023;195: 110207.

Review question

What are the best dietary patterns for reducing cardiovascular risk factors and enhancing blood sugar control in people living with type 2 diabetes?

Background

By the year 2030, it is estimated that more than 10% of the global population will be living with type 2 diabetes, a major risk factor for cardiovascular disease (CVD). Adopting a healthy and nutritious diet is one strategy that can be used to manage type 2 diabetes. But with so many dietary patterns to choose from, it is not clear which one is the most effective for blood sugar control and reducing risk factors for CVD.  

How the review was done

This is a systematic review and network meta-analysis of 73 randomized control trials. The studies were published between 1978 and 2022 and included a total of 5,753 participants.

Key features of the included studies:

• The average age of the participants, all of whom had type 2 diabetes, ranged from 52.3 to 63.7 years.
• Participants followed one of these dietary patterns: low glycemic index (GI) diet (consuming foods that cause slower and smaller increases in blood sugar and are high in fiber); Mediterranean diet (consuming fish, lean meats, whole grains, fruits, vegetables, and plant-based oils); plant-based diet (vegan or vegetarian); high protein diet (equal to or more than 25% of calories from protein); low carb diet (less than 30% of calories from carbs); low fat diet (less than 30% of calories from fats); or moderate carb diet (more than 45% of calories from carbs, more than 30% from fat, and less than 25% from protein).
• Researchers measured changes in body weight, average blood sugar levels, systolic blood pressure, low-density lipoprotein (LDL) “bad” cholesterol, and major adverse cardiovascular events (MACE).
• Results were compared to people in control groups who received no intervention, meaning stayed on their usual diets or received one-time dietary advice.

What the researchers found

Most of the diets reduced weight and improved blood sugar levels in the short- term (6 months). Only the Mediterranean diet reported longer term weight loss benefits at 12 months. Additionally, no short-term or long-term improvements in systolic blood pressure or LDL “bad” cholesterol were demonstrated. Although only the low GI diet produced significant reductions in the risk of major adverse cardiovascular events, all diets showed a trend toward meaningful reductions. Ultimately, no single diet came out on top and more long-term research is required.   

Conclusion

In people living with type 2 diabetes, various dietary patterns can produce short-term improvements in body weight and average blood sugar levels, as well as potentially meaningful reductions in the risk of major adverse cardiovascular events, compared to no intervention.