Are Diet & Exercise Effective in Prevention?


Older Person (2)Programmes that promote dietary change and physical activity are effective in reducing the likelihood that people at risk of developing type 2 diabetes will do so, say new recommendations from the US Community Preventive Services Task Force (Pronk & Remington, 2015).

The task force arrived at its recommendations after a systematic review of 53 studies that described 66 programmes (Balk et al., 2015). Participants in such programmes were also more likely to see an improvement in diabetes and cardiovascular risk factors, such as excess weight and elevated blood glucose levels, lipid levels, and blood pressure, the panel said. “The beneficial effects of combined programs were seen across a wide range of intensity levels,” the task force said.

The Community Preventive Services Task Force, which was created by the US Department of Health and Human Services, comprises an independent group of public health and prevention experts who draw up evidence based recommendations for community preventive services, programmes, and policies. The task force’s recommendations were published online in the Annals of Internal Medicine journal on 13 July.

The recommendations are aimed at adolescents and adults who would be considered at raised risk of type 2 diabetes from having blood glucose levels that are abnormally elevated but not high enough to be classified as type 2 diabetes. These are people with hemoglobin A1c levels of 5.7-6.4%, fasting plasma glucose levels of 100-125 mg/dL, or plasma glucose levels of 140-199 mg/dL after a 75 g oral glucose tolerance test.

The task force’s systematic review said, “Compared with usual care, diet and physical activity promotion programmes reduced type 2 diabetes incidence (risk ratio 0.59 (95% confidence interval 0.51 to 0.66)) (16 studies), decreased body weight (net change –2.2% (–2.9% to –1.4%)) (24 studies) and fasting blood glucose level (net change –0.12 mmol/L (–2.2 mg/dL) (–0.20 to –0.05 mmol/L) (–3.6 to –0.9 mg/dL)) (17 studies), and improved other cardio-metabolic risk factors.”

The evidence to support the premise that programmes promoting diet and physical activity reduced the risk of type 2 diabetes was “strong,” the task force said. However, it added that the effectiveness of such programmes in reducing cardiovascular disease, diabetes related complications, and death was unclear because few studies reported these outcomes or had results from long term follow-up.

The critical components of effective programmes included using trained providers who worked with

the participants for at least three months; some combination of counselling, coaching, and extended support; and multiple sessions related to diet and physical activity. An analysis of 12 studies that directly compared programmes found that people who received more intensive programmes – in terms of the number of sessions, individual sessions, and additional personnel, for example – were less likely to develop diabetes.

None of the studies found any long term harms directly related to programme participation. A separate economic review of 28 studies found that the interventions were cost effective (Li et al., 2015).

In an accompanying editorial Ronald T Ackermann, of Northwestern University Feinberg School of Medicine in Chicago, Illinois, noted that, although combined diet and physical activity promotion programmes were an effective “prescription” for diabetes prevention, only one in 13 of the 86 million US people with pre-diabetes were aware of their high risk for developing the condition.

He wrote, “Healthcare providers should assume a greater role in performing recommended screening and linking high risk patients with combined diet and physical activity promotion programmes.” (Ackermann, 2015).

Reference (Whole Article)

BMJ 2015;351:h3785

References (In Article)

Pronk, N.P. & Remington, P.L, on behalf of the Community Preventive Services Task Force. (2015) Combined Diet and Physical Activity Promotion Programs for Prevention of Diabetes: Community Preventive Services Task Force Recommendation Statement. Annals of Internal Medicine. Published online 14 July, doi:10.7326/M15-1029.

Balk, E.M,, Earley, A., Raman, G., et al. (2015) 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. Annals of Internal Medicine. Published online 14 July, doi:10.7326/M15-0452.

Li, R., Qu, S., Zhang, P., et al. (2015) Economic Evaluation of 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. Annals of Internal Medicine. Published online 14 July, doi:10.7326/M15-0469.

Ackermann, R.T. (2015) Diabetes Prevention at the Tipping Point: Aligning Clinical and Public Health Recommendations. Annals of Internal Medicine. Published online 14 July,  doi:10.7326/M15-1563.

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