The Community Preventive Services Task Force’s guidelines for using diet and exercise to prevent diabetes were published in the Annals of Internal Medicine in July 2015. The task force reviewed the evidence to determine whether these programs are effective for people at risk for type 2 diabetes.1
The Community Preventive Services Task Force makes recommendations about important public health interventions. These findings were based on 53 studies (of 66 programs) published between January 1991 and February 2015.1
“Our task was to be an independent advisor to practitioners. We did a systematic review of the evidence, looking at the strength and quality of all the studies,” said task force member Patrick L. Remington, MD, MPH, professor and associate dean for public health at the University of Wisconsin School of Medicine and Public Health in Madison.
This is the first time the task force has made recommendations on physical activity and diet programs to prevent type 2 diabetes. The target population was people at risk.
“There are all sorts of guidelines for types of exercise and type of diet for diabetes prevention. This was the first to focus specifically on people with prediabetes who participated in structured, extended and combined physical activity and diet programs,” Remington said.
Key Findings of the Task Force
“The strength of these recommendations [is] that they recognize weight loss through diet and exercise as a key intervention. Highlights for me were the findings that multiple different interventions and providers were successful, and that more intense interventions led to better results,” said Bipan Chand, MD, associate professor and director of the Loyola Center for Metabolic Surgery and Bariatric Care at Loyola University Medical Center in Maywood, Illinois.
Key findings of the task force include:1
- Combined programs that promote a combination of physical activity and diet can help patients at risk for type 2 diabetes normalize blood glucose, reduce weight, lower blood pressure (BP) and improve lipid profile.
- The programs were effective across a wide range of intensity, settings and facilitators. Median program length was 12 months, but programs ranged from 3 months to 6 years. Some programs were tailored to individuals, and some were group programs. Facilitators included nutrition and exercise counselors, nurses, physicians, psychologists and trained laypersons. Almost all sustained programs were beneficial.
- Programs that were more intensive, had more sessions, and more individual counseling resulted in more weight loss and fewer cases of diabetes.
- Older participants saw the most improvement, but the benefits applied to all participants, even after adjusting for such variables as race, sex, ethnicity and socioeconomic status.
- The programs were cost effective. A number of the studies reviewed cost. The median cost to implement these programs was less than $700 per person. Studies that estimated incremental cost-effectiveness ratios found a median savings of almost $14,000 per quality-adjusted life year.
Target Population: Who Is at Risk?
The task force defined people at risk for type 2 diabetes as having an abnormal blood glucose level, including HbA1c levels between 5.7% and 6.4% and fasting glucose between 100 mg/dL and 125 mg/dL.
“I would have liked to see them include BMI, central obesity and family history, as these are important predictors of diabetes,” said Chand.
Although the review of studies found good evidence for weight loss, blood sugar, BP and lipid levels, the effectiveness of the programs for reducing cardiovascular disease (CVD), diabetes complications and death were unclear since few studies reported on long-term outcomes.1
“We wanted to focus on prediabetes, but clinicians should use their clinical judgment. I am absolutely confident that these programs will be effective for people with other diabetes risk factors and will help prevent future diabetes complications and cardiovascular disease,” said Remington.
Key Takeaways for Primary Care Providers
“Primary care doctors should recognize that these programs work, but they do not need to work in isolation. It takes a team of providers that may include exercise therapists, dietitians and behavioral therapists. You can’t do it all. Primary care docs need to make use of community programs and hospital programs in their areas that have these teams in place,” said Chand.
Remington agrees that primary care doctors cannot implement these programs on their own.
“Primary care should take a leadership role in disseminating these benefits. They should work with insurers, employers and community health systems. We know that these programs work, [but] we don’t know as much about how to implement them effectively,” said Remington.
Filling in the Gaps: A Long Way to Go
The task force identified several evidence gaps that could benefit from future research. These include the usefulness of programs delivered online, strength of individual vs. group programs, community programs vs. primary care programs and more information on group programs led by trained laypersons.1
There is plenty of evidence that these programs work, but less evidence that they are working in the long run. “There is emerging evidence that these programs are having an impact, but don’t forget it took 30 to 40 years to turn the tide against smoking, and we are still not done,” Remington said.
In 2010, Congress authorized the Centers for Disease Control and Prevention (CDC) to establish the National Diabetes Prevention Program. There are some notable successes in isolated programs across the country.1
“We have been successful in pockets of the population but not nationally. Statistics on diabetes and obesity are going in the wrong direction and are expected to continue that way for the near future. We still have a long way to go,” Chand said.
It will take a while to change direction. Primary care providers are usually the primary resource for people at risk for type 2 diabetes, and they will be the key to the success of these programs. They need to be aware of the benefits of diet and exercise programs and be the primary promoters of these benefits.1
- Pronk NP et al. Ann Intern Med. 2015;doi:10.7326/M15-1029.