Exercise and diet

Exercise and diet reduces the odds of developing type 2 diabetes by 42% among adults at high risk for diabetes.

food  exercise

Why are exercise and diet important?

  • Type 2 diabetes is the most common type of diabetes and its development is associated with obesity, decreased physical activity, and poor dietary habits. Weight loss and nutritional advice are important aspects of diabetes management. The prevalence of type 2 diabetes is increasing in low- and middle-income as well as high-income countries. Exercise and dietary modifications can prevent the development of diabetes while also preventing obesity and reducing the risk of other, related conditions, such as high blood pressure.

Do they work?

  • Exercise and diet reduce the incidence of diabetes among high risk adults by 42%. In addition, all-cause mortality, cardiovascular mortality, socioeconomic effects, and serious adverse effects were considered between standard treatment groups and intervention groups.

Equity: Do they work in the disadvantaged?

  • There is no reason to indicate that diet and exercise would be less effective among other populations assuming that high fibre and lower fat foods are easily accessible and the local environment supports activities such as walking or jogging.

Intervention Delivery

    • The exercise interventions varied between studies but included promoting physical activity and supervised exercise programs. Most exercises were walking and cycling. Exercise was promoted alone or in combination with dietary modifications.
    • The diet interventions focused mainly on reducing calories, reducing fat intake, and increasing fibre intake.
    • Some studies included motivational strategies and goal setting.
    • The interventions were facilitated by physicians,, or other health care providers, such as dieticians, nutritionists, and physiotherapists.
    Population and Setting
    • The studies were conducted in China, Finland, India, Japan, Sweden, United Kingdom, and United States.
    • Participants were at high-risk for development type 2 diabetes.

    Summary of Findings [SOF] Table: Diet plus physical activity versus standard treatment for prevention or delay of type 2 diabetes mellitus

    Patient or population: People at high risk of developing type 2 diabetes mellitus.
    Settings: Outpatients
    Intervention: Diet plus physical activity
    Comparison: Standard treatment

    Outcomes

    Anticipated absolute effects

    Relative effect
     (95% CI)

    No of Participants
    (studies)

    Quality of the evidence
    (GRADE)

    Without exercise+diet

    With exercise+diet  (95% CI)


    Incidence of type 2 diabetes
    257 per 1000
    111 fewer per 1000 (from 98-128 fewer)
    RR 0.57 (0.50-0.64)
    4511 (11)
    Moderate1
    All-cause mortality
    (Follow-up: up to 6 years mean duration 3.5 years)    		5 per 10000 fewer per 1000 (from 3 fewer to 7 more)RR 1.12 (0.50-2.50)4099 (10)Very Low2
    Cardiovascular mortality2 per 10000 fewer per 1000 (from 1 fewer to 7 more)RR 0.94 (0.24-3.65)3263 (7)Very Low1
    Socioeconomic effects
    (Follow-up: up to 3 years)    		Mean direct medical cost of intervention ranged from 61 to 184 USDMean direct medical cost of intervention ranged from 225 to 3625 USD2775 (4)Low3
    Serious adverse effects [SAE]
    (Follow-up: up to 6 years)    		In 1 trial, 1/51 participants in the diet plus physical activity group compared with 0/51 participants in the standard treatment group experienced SAE.
    1 trial reported that no adverse effects occurred.
    In 4 other trials, it was clearly described that SAE data had been collected but data were not presented.    		250 (2)Low4
    Adverse Events: One study reported musculoskeletal conditions in the exercise group.
    About quality of evidence (GRADE) High quality (High): Further research is very unlikely to change our confidence in the estimate of effect.
    Moderate quality (Moderate    ): Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
    Low quality (Low    ): Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
    Very low quality (Very low    ): We are very uncertain about the estimate.

    1. Downgraded by one level because of other bias (early termination of three trials due to benefit providing the majority of data)
    2. Downgraded by three levels because of risk of bias including possible publication and other bias, inconsistency, and imprecision.
    3. Downgraded by two levels because of risk of bias and imprecision.
    4. Downgraded by two levels because of reporting bias and imprecision.

    Relevance of the review for disadvantaged communities

    Findings

    Interpretation

    Equity – Which of the PROGRESS groups examined

     

    Of the 12 included studies, 2 were conducted in low- and middle-income countries and the remainder in high-income countries.

    Diet and exercise interventions are effective in low-, middle-, and high-income countries.

    All participants were adults between 45 and 63 years old.

    The effect of diet and exercise for preventing type 2 diabetes in children, adolescents, and seniors is not clear.

    Patients with chronic conditions that require specific diet or exercise recommendations were excluded.

    It is not clear whether diet and exercise interventions can prevent type 2 diabetes in patients with other chronic conditions.

    Equity Applicability

     

    The participants were all individuals at high risk for developing type 2 diabetes.

    The results are applicable to individuals at high risk of developing type 2 diabetes. However, the interventions were effective across different settings so the results are applicable for individuals in settings that are different from those included in the review.

    Cost-equity

     

    Three studies examined cost effectiveness of exercise and diet interventions and determined them to be cost-effective from the perspective of a health care system.

    Policymakers implementing a diet and exercise intervention need to consider the costs of the intervention within their settings. Possible costs include:

    - written patient materials

    - diet and exercise counseling provided by health care provider or other professional

    - additional follow up appointments to monitor effectiveness of the intervention

    Further research is needed to determine the cost of these interventions.

    For the patient, the cost of diet and exercise to prevent type 2 diabetes is much more affordable than the cost of medications required to manage diabetes. There is little to no additional costs for people to exercise. In some settings healthier diets (high in fibre, low in fat)  may be more costly. More research is needed to determine whether exercise alone is effective in preventing type 2 diabetes.

    Monitoring & Evaluation for PROGRESS Groups

     

    Diet and exercise are effective in preventing type 2 diabetes among high risk individuals. However, the effectiveness may vary outside of research settings.

    Policymakers implementing diet and exercise interventions should be sure to include a systematic to monitor the effectiveness of the program.

     Comments on this summary? Please contact Jennifer Petkovic.

    Drafted by Chaeyon Lee