Three cardiologists, including the 2015-2016 president of the American College of Cardiology, review the evidence in support of lifestyle modification for diabetes management or remission.
Type 2 diabetes (T2D) is a costly chronic illness that is increasing in prevalence and associated with significant health problems, including cardiovascular disease (CVD).1 In fact, CVD is listed as the cause of death in nearly 65% of individuals with diabetes.2
Historically, T2D was labeled a “coronary artery disease equivalent”in light of the 7-year risk of myocardial infarction (MI) equaling that of a person without diabetes who is post-MI3 in the restatin-treatment era and the marked improvement in adverse cardiac events with statin therapy.4 Given this grave prognosis, and with longstanding work showing diabetes remission from lifestyle interventions as far back as the 1940s,5 there is no better and more economical way to treat this epidemic.
Diabetes and CVD share multiple modifiable lifestyle risk factors, such as obesity and physical inactivity, that tend to comingle for many adults, adding to the threat of severe adverse effects already present from a genetic predisposition and other acquired risk factors.6-8 In the United States, diabetes affects at least 29.1 million individuals, the equivalent of 9.3% of the entire population and 12.3% of the adult population.9 Depending on the cohort surveyed and the definition used, another 5.4 million are estimated to have undiagnosed diabetes.9
Diabetes-related care accounts for more than $1 of every $5 spent on healthcare in the United States, equating to $245 billion in total costs in 2012.10 Not surprisingly, average medical expenses are more than twice as high for a person with diabetes as they are for a person without diabetes.10
Although drug therapy may be required to control metabolic risk factors, particularly when they arise from genetic aberration and aging, modification of life habits remains at the heart of the public health strategy for prevention of CVD and diabetes. Research has repeatedly demonstrated the benefits of lifestyle interventions,11 including engaging in physical activity, adopting healthier eating practices, managing stress, and using social-environmental support to initiate and sustain health-related behaviors.
Several advances in diabetes management over the past few decades have improved the health of many patients and should not be understated. However, these advances are beneficial only to the extent that patients use them appropriately. To do so requires knowledge, problem-solving skills, motivation, environmental support and effective coping skills for life’s many stressors. Additionally, due to these behavioral challenges of daily diabetes self-management and despite the technological advances in diabetes care, patients have limited resources, perhaps even limited free will, in their management decisions. Despite this, research still shows that individual behavior can be shaped and behavioral interventions can help patients make better choices for their own diabetes self-management, even in the context of difficult circumstances.
Diabetes self-management is central to diabetes care overall, and much of this entails individual behavior change, particularly around dietary patterns and physical activity. Published recommendations for the treatment of people with diabetes assert the importance of diet, exercise, and education to diabetes treatment.12,13 Nutrition is key in the management of diabetes and CVD risk prevention. Current recommendations for patients with diabetes center around a dietary pattern that emphasizes fruits, vegetables, reduced saturated fat, and low-fat dairy products, as well as modification of macronutrient intake to accommodate individual needs for the distribution of calories and carbohydrates throughout the day. The Dietary Approaches to Stop Hypertension, Mediterranean, low-fat, and monitored carbohydrate diets are effective for controlling hyperglycemia and lowering CVD risk factors.12 The Prevención con Dieta Mediterránea (PREDIMED) trial was a randomized trial that found a 30% reduced risk of CVD events in diabetic patients randomized to the Mediterranean diet, suggesting that this diet may promote CVD risk reduction in this population.14
Dietary content heavily impacts the development of diabetes. In the Adventist Health Studies, the prevalence of diabetes was lower in vegetarians than in nonvegetarians,15 an effect likely mediated by the lower body weights of the vegetarians. And when compared with a standard American diet, the prevalence of diabetes was reduced by 23% with a semi-vegetarian diet, 38% by consuming a pesco-vegetarian diet, 55% with a lacto-ovo-vegetarian diet, and 75% with a vegan diet. Dietary interventions with a whole foods plant-based nutrition (vegan diet) have even been shown, through a small randomized trial, to reduce the pain levels in diabetic neuropathy. Similarly, foods with a lower glycemic index have been associated with a lower risk of diabetes development in the Nurses Health Studies.17 In contrast, the Health Professionals Follow-up Study indicated that eating processed meats increases the risk of developing diabetes.16
More recently, several trials have shown surprising outcomes for a commonly consumed food: eggs. One of the larger of these analyses of 14 studies found that for those who consumed the most eggs, there were 19% and 68% increased risks for developing CVD and diabetes, respectively, compared with those who ate the fewest eggs. Further, for those who already had diabetes, the risk for developing heart disease from eating the most eggs jumped to 83%. The authors concluded, “There is a dose-response positive association between egg consumption and the risk of CVD and diabetes.”19
Research has also demonstrated the benefits of meditation, both mindfulness and transcendental, for diabetes management. A randomized trial published in JAMA found that meditation reduced blood pressure, increased insulin resistance, and significantly reduced the rates of CVD events.20
Multiple epidemiological studies suggest that both obesity and physical inactivity are independent risk factors for diabetes, and the reduction or elimination of such factors appears to be related to prevention and management of this disease.21 Further, physical activity and weight loss improve blood pressure and lipid levels, thereby positively affecting other CVD risk factors. This robust and consistent observational evidence has given rise to large-scale randomized controlled trials that have used lifestyle intervention (including behavioral strategies for reinforcement of prescribed changes in nutritional intake, physical activity, or both) in populations at high risk of developing diabetes. The aim of these trials was to reduce the rate of incident diabetes and ameliorate risk factor profiles associated with both diabetes and cardiovascular morbidity and mortality.21,22 For instance, the Diabetes Prevention Study and the Diabetes Prevention Program demonstrated that dietary improvement and increased physical activity reduced the incidence of diabetes by nearly 60% in 4 years.23,24 The Da Qing study later compared diet, exercise, and diet plus exercise with a no-treatment control group and found that all 3 lifestyle approaches reduced the risk of developing diabetes by 31% to 46%.25 Later, the Finnish Diabetes Prevention Study demonstrated similar results in over 500 overweight subjects with impaired glucose tolerance—lifestyle intervention designed to produce weight loss improved dietary intake and physical activity and reduced the risk of diabetes by 58%.6,7
More recently, the Look AHEAD (Action for Health in Diabetes) study, conducted from 2001 to 2012, provided extensive longitudinal data on the effect of an intensive lifestyle intervention— targeting weight reduction through caloric restriction and increased physical activity—on CVD rates and risk factors among adults with diabetes.26 Published in 2013, the primary results of Look AHEAD showed that greater weight loss was observed in the intervention arm (8.6%) compared with the usual care arm (0.7%).Additionally, patients in the intervention group had improved physical fitness and high-density lipoprotein (HDL) cholesterol levels, greater reductions in glycated hemoglobin (A1C) and waist circumference, and required less pharmacotherapy for glucose, blood pressure, and lipid control. Although the trial was stopped early due to futility (possibly from discontinuation of cardioprotective drugs, such as statins), the results inform clinicians that increased physical activity and improvements in diet can safely lead to weight loss and a reduced requirement for medications to control CVD risk factors without a concomitant increase in the risk of cardiovascular events.
The Italian Diabetes and Exercise Study (IDES) was another randomized trial designed to examine the effects of an intensive exercise intervention strategy on modifiable CVD risk factors in diabetics. The subjects were randomized to an exercise group or control group (structured individualized counseling alone) for 12 months. Compared with the control group, supervised exercise produced significant improvements in physical fitness, A1C, systolic and diastolic blood pressures, HDL- and low-density lipoprotein cholesterol levels, waist circumference, body mass index, insulin resistance, inflammation, and coronary heart disease (CHD) risk scores.27
Ensuring a Sustained Impact
These important lines of research, while demonstrating the benefits of behavioral interventions, also raise many questions. To start, what are the mechanisms of action of these interventions? A meta-analysis by Hood et al suggests that multicomponent interventions targeting emotional, social, or family processes that facilitate diabetes management are more potent than interventions that target a single direct behavioral process.28 Identifying active ingredients and determining the necessary doses of those ingredients would allow both clinicians and patients to focus resources on the most important areas of an intervention. How can we maintain lasting behavioral changes once they have been initiated? Results from many weight loss interventions highlight the need for more consideration of behavior maintenance strategies.29 Lastly, how can we effectively disseminate interventions to the larger diabetic population? Even the most effective interventions are useful only to the point that patients have access to them. The internet, telemedicine, peers and community health workers, and mobile electronic devices all hold promise in this regard.
The magnitude of the behavioral diabetes research agenda is impressive, although much work is still needed to determine the optimal approach to diabetes management. Until then, the lifestyle interventions discussed give patients the behavioral technology they need to more effectively navigate their world with diabetes.They also give healthcare providers greater ability to inform and support their patients with diabetes. Encouraging patients to self-manage their disease, as well as engaging all stakeholders in the necessary behavioral changes, can positively influence the long-term treatment outcomes of patients with diabetes.
Finally, educating physicians and allied health professionals on the power of lifestyle changes through diet, exercise and physical activity, and mindfulness is a critically underestimated and underfunded approach. Because of minimal nutrition training in medical school and the lack of exposure to lifestyle medicine, many healthcare providers do not counsel, implement, or coach patients to make these changes. Recently, the American College of Cardiology hosted a half-day intensive within its 2016 Annual Scientific Sessions that solely focused on lifestyle modification. Education from leading experts in the realm of lifestyle and nutrition was delivered with an incredibly positive response to a standing room-only audience. The intensive session started with a debate about commonly held nutrition misconceptions and was followed by sessions on the latest in behavioral modification and motivational interviewing, smoking cessation, and scientific evidence around the topics of mindfulness, stress reduction, love, and connection. Overall comments from the audience showed a true desire to learn more about these topics and ways to implement them in common practice.
In summary, treatment for diabetes and the associated CVD has come a very long way. Behavioral intervention, in the form of lifestyle medicine, is an approach that both minimizes cost and maximizes yield in dealing with both. Now is the time for the medical community, as a whole, to become aware of this approach and review the research that has often been ignored despite excellent results. While implementation is the major barrier, along with patient compliance and uptake, the time and effort required leads to lasting results that are well worth the initial investment. Hena N. Patel, MD, and Kim A. Williams, MD, FACC, are with the Rush University Medical Center, Division of Cardiology, Chicago. Andrew M. Freeman, MD, FACC, is with the Department of Medicine, Division of Cardiology, National Jewish Health, Denver. Dr Williams served as the 2015-2016 president of the American College of Cardiology. References
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