Diet and exercise promotion programs reduce risk of type 2 diabetes

Balk EM, Earley A, Raman G, et al. Combined diet and physical activity promotion programs to prevent type 2 diabetes among persons at increased risk: A systematic review for the community preventive services task force Ann Intern Med. 2015; 163: 437-451.

Review question

Do diet and exercise promotion programs prevent type 2 diabetes in at-risk adults and children?

Background

There are approximately 387 million adults living with diabetes worldwide and this number is expected to almost double by 2035. Effective prevention programs – such as promoting diet and exercise – are needed to slow the number of new diabetes cases. However, since these programs are relatively new, few studies have examined the effectiveness of combined diet and exercise promotion programs in the community and how they affect rates and risk of type 2 diabetes (T2D).

How the review was done

This is a systematic review and meta-analysis of 53 studies (randomized controlled trials and single-group studies lasting longer than 6 months) published from 1991 to 2015. Study participants included adults or children with prediabetes (higher than normal blood sugar levels which put people at risk of diabetes).

The studies all measured the impact of diet and exercise programs on preventing T2D in people at high-risk.  The programs had to include at least 2 sessions (in person or online) offering advice about improving both diet and activity levels over at least 3 months.  The researchers measured the number of people who developed T2D, as well as blood sugar levels, body weight and health factors associated with T2D such as indicators of heart or kidney disease, nerve damage (neuropathy) and blood pressure.

What the researchers found

The majority of included studies focused on adult participants, rather than children. Participants in diet and exercise promotion programs were significantly less likely to develop diabetes and more likely to return to normal blood sugar levels than those who received the usual care and these effects appeared to last in the long term.  

Diet and exercise promotion programs also improved weight, blood pressure and cholesterol levels compared with usual care.  Adults in more intensive programs lost more weight and were less likely to develop diabetes than those in less intensive programs.  More research is needed to measure the effects of these types of programs on other diabetes-related risks such as heart disease.

Conclusion

Combined diet and exercise promotion programs help prevent new cases of diabetes and improve risk factors (eg. weight, blood pressure, blood sugar levels) for people with prediabetes.