Diabetes: Combined Diet and Physical Activity Promotion Programs to Prevent Type 2 Diabetes Among People at Increased Risk

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Findings and Recommendations

The Community Preventive Services Task Force (CPSTF) recommends combined diet and physical activity promotion programs for people at increased risk of type 2 diabetes to reduce new-onset diabetes. Combined diet and physical activity promotion programs also increase the likelihood of reverting to normoglycemia (normal blood sugar) and improve diabetes and cardiovascular disease risk factors, including overweight, high blood glucose, high blood pressure, and abnormal lipid profile.

Based on the evidence, combined diet and physical activity promotion programs are effective across a range of counseling intensities, settings, and implementers. Programs commonly include a weight loss goal, individual or group sessions (or both) about diet and exercise, meetings with a trained diet or exercise counselor (or both), and individually tailored diet or exercise plans (or both). Higher intensity programs lead to greater weight loss and reduction in new-onset diabetes.

Economic evidence indicates that combined diet and physical activity promotion programs to prevent type 2 diabetes among people at increased risk are cost-effective.

The full CPSTF Finding and Rationale Statement and supporting documents for Diabetes Prevention and Control: Combined Diet and Physical Activity Promotion Programs are available in The Community Guide Collection on CDC Stacks.

Intervention

Combined diet and physical activity promotion programs aim to prevent type 2 diabetes among people who are at increased risk of the disease. These programs actively encourage people to improve their diet and increase their physical activity using the following:

  • Trained providers in clinical or community settings who work directly with program participants for at least 3 months
  • Some combination of counseling, coaching, and extended support
  • Multiple sessions related to diet and physical activity, delivered in-person, or by other methods

Programs may also use one or more of the following:

  • Providers who are diet counselors of different specialties (for example, nutritionists, dietitians, diabetes educators), exercise counselors of different specialties (for example, physical educators, physiotherapists, trainers), physicians, nurses, trained laypeople, and others
  • A range of intensity in the counseling, with numerous or few sessions, longer or shorter duration sessions, and individual or group sessions
  • Individually tailored or generic diet or physical activity programs
  • Specific weight loss or exercise goals
  • A period of maintenance sessions following the primary core period of the program

Program participants may be considered at increased risk of type 2 diabetes if they have blood glucose levels that are abnormally elevated, but not high enough to be classified as type 2 diabetes. Participants may also be identified using diabetes risk assessment tools.

About The Systematic Review

The CPSTF finding is based on evidence from a systematic review of 53 studies that described 66 programs (search period January 1991 — February 2015).

Study Characteristics

  • Programs lasted from three months to six years (median 12 months).
    • The core period lasted between one month and five years (median 6 months).
    • Maintenance periods (in 28 programs) lasted between four and 68 months, with a median of 12 months.
  • Programs provided between 0 (virtual sessions only) and 72 sessions, with a median of 15 sessions.
  • Programs used individual face-to-face meetings (40 programs included individual diet sessions, 41 programs included individual exercise sessions), group meetings (diet: 41 programs, exercise: 39 programs), or both (diet: 24 programs, exercise: 24 programs). Five programs were conducted via web-tools, social networking, email, text messaging, video, or a combination of these, with no in-person sessions.
  • Sessions were led by different combinations of trained diet counselors including dietitians, nutritionists, or others (37 programs); trained exercise counselors including physical trainers or others (26 programs); nurses (15 programs); physicians or psychologists (8 programs); and trained laypeople (13 programs).
  • Programs included specific weight loss goals (42 programs), diet goals (19 programs), and physical activity goals (32 programs).
  • Programs included individually tailored plans for diet (16 programs) and physical activity (23 programs).
  • Studies were conducted in the United States (21 studies), Europe (17 studies), and other countries.

Summary of Results

The systematic review included 53 studies that described 66 programs.

  • Among populations at increased risk of type 2 diabetes, combined diet and physical activity promotion programs led to improvements in health outcomes and risk factors for type 2 diabetes and cardiovascular disease compared with usual care.
    • The proportion of people who developed type 2 diabetes decreased by a median of 11 percentage points (16 studies).
    • The proportion of people who achieved normal blood sugar (normoglycemia) increased by a median of 12 percentage points (6 studies).
    • Body weight was reduced by an average of 2.2% (24 studies).
    • Fasting blood glucose was reduced (improved) by an average of 2.2 mg/dL (17 studies) and hemoglobin A1c (a measure of long-term glucose levels) was reduced (improved) by an average of 0.08 percentage points (8 studies).
    • Blood pressure (17 studies) and cholesterol levels (13 studies) also were improved.
  • The effect on mortality was unclear. Mortality was reduced by 2 to 10 percentage points (2 studies) or by 0.6 per 1000 person-years (1 study) over 3 to 23 years of follow-up. However, this benefit was statistically significant in only one study, and in that study, only among women.
  • Regardless of program features, almost all programs led to weight loss, reduced risk of diabetes, or both. However, among 12 studies with direct comparisons, more intensive programs (based on features such as number of sessions, individual sessions, and additional personnel) resulted in greater weight loss and lower rates of diabetes than less intensive programs.
  • In studies of programs that used protocols outlined by the U.S. Diabetes Prevention Program (DPP) study or Finnish Diabetes Prevention Study (DPS), or modifications of them, participants lost more weight (3% of initial body weight) than participants in programs not based on DPP or DPS (1.6% of initial body weight). Reductions in risk of developing diabetes were similar between studies of different programs.

Summary of Economic Evidence

An economic review of 28 studies (search period January 1985 — April 2015) shows that combined diet and physical activity promotion programs for people at increased risk for type 2 diabetes are cost-effective. All monetary values reported are in 2013 U.S. dollars.

Cost of programs:

  • All programs: median $653 per participant (12 studies)
  • Group-based programs: median $417 per participant (8 studies)
  • Programs that translated the U.S. DPP into community or primary care settings: median $424 per participant (8 studies)

Cost-effectiveness of the program (from the health system perspective, which included only the direct medical costs of the programs and healthcare costs averted, based on either data collected in actual programs or estimates from simulation models):

  • Cost per quality-adjusted life year (QALY) saved:
    • All programs: median $13,761 (16 studies)
    • Group-based programs: median $1,819 (5 studies)
    • Individual-based programs: median $15,846 (5 studies)
  • Cost per disability-adjusted life year (DALY) averted:
    • $21,195 and $50,707 (2 studies)
  • Cost per life year gained (LYG):
    • Median $2,684 (6 studies)

The variation in program costs per participant is partly explained by the number of sessions, delivery mode of the core sessions (individual vs. group), setting (clinical trial vs. community or primary care), and type of personnel used (health professionals vs. trained laypeople).

Applicability

The CPSTF finding is applicable to men and women in the United States who are at increased risk for type 2 diabetes, regardless of race/ethnicity, socioeconomic level, setting (urban or rural). The finding applies to programs offered through healthcare and community-based settings.

Evidence Gaps

  • How does program effectiveness vary by population demographics (e.g., race/ethnicity, SES, educational attainment, age, cognitive or physical disabilities)?
  • How effective are programs delivered via the Internet, email, apps, or social networking?
  • What is the relative effectiveness of individual and group sessions?
  • What are effective structures for the maintenance phase of these programs to help participants continue their improvements to diet and physical activity following completion of the core phase?
  • What are long-term effects of community-based programs on diabetes incidence, weight loss, other diabetes risk factors, morbidity, and mortality?
  • What are recruitment and attrition rates? Why don’t all referred clients follow-up and why do some participants drop out? What are effective strategies to recruit and retain clients?
  • What are the economic costs and benefits of programs implemented in community and primary care settings? Evaluations should include group-based programs delivered by trained laypeople.
  • What are the costs of identifying and recruiting eligible individuals to participate?
  • What are the costs associated with program implementation in community or primary care settings, and how can they be lowered? Costs include start-up costs, costs of program delivery (by program duration and setting), and costs to different stakeholders and society as a whole.
  • What are long-term economic benefits of a program? What are actual heath care expenditures averted in total, by expenditure category? Ideally, an assessment would follow an intervention cohort and its comparison group for a long period of time.

Implementation Considerations and Resources

  • In 2010, the U.S. Congress authorized CDC to establish the National Diabetes Prevention Program (National DPP), an alliance of public and private organizations (including insurers) managed by CDC to achieve wide-scale implementation and coordination of lifestyle change programs to prevent or delay type 2 diabetes. As of May 2014, more than 500 organizations in all states and the District of Columbia have applied for CDC recognition for their diabetes prevention programs. More information about the National DPP can be found at www.cdc.gov/diabetes/prevention.
  • Combined diet and physical activity promotion programs have been successfully implemented by several national and state-wide organizations, the majority of which are part of the National DPP.
  • Healthcare providers are usually the primary resource for individuals newly diagnosed as being at increased risk of type 2 diabetes. Providers need to know the benefits of combined diet and physical activity promotion programs and be aware of local programs, which may be offered by community centers, insurer-run programs, or non-profit or other private contractors among others.
  • Organizations implementing combined diet and physical activity promotion programs may want to address factors that make it difficult for some people to participate. Examples include limited ability to pay for program services; limited time to cook or exercise due to work schedules or childcare needs; limited access to inexpensive and healthful food, safe and convenient places to exercise and transportation there; and cognitive or physical disabilities.

Crosswalks

Healthy People 2030 icon Healthy People 2030 includes the following objectives related to this CPSTF recommendation.