People with diabetes are at much higher risk for cardiovascular disease(CVD) than the average population. Evidence-based, prioritized, and strategic management of CVD risk factors among people with diabetes is necessary for the improvement of its burden on disability, morbidity, mortality, and high health care costs. Risk factors for diabetes and CVD are similar, and most can be effectively decreased by lifestyle modification. Medical nutrition therapy and other lifestyle recommendations for CVD prevention and treatment are discussed.
Lifestyle modification is effective in the improvement of many cardiovascular risk factors,1,2 and among those at high risk for cardiovascular disease (CVD), the benefits of lifestyle modification are proportionally higher.3 Risk assessment for primary prevention of CVD and stroke should include regularly updated family history, smoking status, food and nutrition patterns, alcohol intake, physical activity, blood pressure, body mass index (BMI), waist circumference, pulse, fasting serum lipoprotein profile (or total and HDL cholesterol if fasting is unavailable), and fasting blood glucose.4 People with diabetes are at a three- to fourfold increased risk for CVD, and this increase is particularly evident in younger age groups and women. Diabetes has been designated as a “CVD risk equivalent—that is, persons with diabetes have the equivalent CVD risk as persons with preexisting CVD and no diabetes.”1 Both diabetes and CVD are challenging to the interdisciplinary health care team.
Evidence-based, prioritized, and strategic management of CVD risk factors among people with diabetes is necessary for the improvement of its burden on disability, morbidity, mortality, and high health care costs. Overall, CVD accounts for > 35% of all deaths in the United States, which in 2004 was at a rate of 2,400 people dying each day in the general population, 17% of them being < 65 years of age.5 Pathogenic processes and risk factors for diabetes and CVD are similar, and most patients with type 2 diabetes die prematurely from a cardiovascular event.6 CVD is also among the most preventable health problems in the nation.5 Therefore,the strategic use of evidence-based practice guidelines can improve practitioners' efforts towards prevention and treatment of CVD among people with diabetes.
Hypertension affects nearly one in three adults in the United States,7,8 and it has been argued that hypertension management is most crucial for people with diabetes based on epidemiological analyses and randomized clinical trials.1 Hypertension is defined as systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg or current use of an antihypertensive medicine.9 Lifestyle factors that may lower blood pressure are sodium restriction; weight reduction or physical activity programs; and reduction of excessive alcohol intake.3 Every routine diabetes visit should include a blood pressure measurement, and if values are 130–139 mmHg for systolic blood pressure or 80–89 mmHg for diastolic blood pressure, lifestyle modification should be promoted,without drug therapy. Drug therapy along with lifestyle modifications should be started at ≥ 140 mmHg for systolic blood pressure or ≥ 90 mmHg for diastolic blood pressure.1
To assist practitioners, the American Dietetic Association has developed the Evidence Analysis Library(EAL).10 These evidence-based nutrition practice guidelines for various topics, diseases, and conditions address important nutrition practice questions and can be found at the American Dietetic Association's EAL Web site(www.adaevidencelibrary.org). Access to the executive summary of recommendations in the EAL Web site is open to the general public, but more details are available to registered dietitians(RDs) and other professionals who are members of the American Dietetic Association or the American Association of Diabetes Educators and to other EAL subscribers. The recommendations in the EAL Web site are graded as strong,fair, weak, consensus, and insufficient evidence. An in-depth explanation of these ratings is available on the EAL Web site.10
Cardioprotective Medical Nutrition Therapy
Lifestyle changes improve the lipid profile of people with diabetes and should be a priority among these individuals.1 Lipid profiles improve when there is a reduction of saturated fat and cholesterol intake, weight loss when appropriate, and an increase in dietary fiber and physical activity.1,11 In terms of medical nutrition therapy (MNT) to prevent CVD for people with diabetes, it is important to note the following: an optimal combination of macronutrients to prevent CVD has not been determined and may not even exist;it varies according to individual circumstances.2,12
The American Diabetes Association (ADA) and the American Dietetic Association have published nutrition therapy recommendations and interventions that are very similar but use different processes.2,12 A comparison of these recommendations is available at www.dce.org/links/jada/00448.htm. The American Dietetic Association's evidence-based nutrition practice guidelines (EBNPG) use a format adopted from Guidelines Elements Model and criteria established by the National Guidelines Clearinghouse,which is a database of evidence-based clinical practice guidelines created by the Agency for Healthcare Research and Quality.13,14 Quality criteria from the Appraisal of Guidelines Research and Evaluation Instrument are used as the basis for development and as the evaluation tool before publication.15
To answer the question, “What is the evidence supporting specific nutrition interventions in studies of a minimum 1-year duration for the prevention of CVD in people with diabetes?,” the American Dietetic Association EBNPG reviewed a total of 12 studies and concluded that nutrition interventions such as a Mediterranean dietary pattern and multifactorial nutrition interventions reduce the risk for the development of CVD.2 To answer the question, “What is the evidence supporting specific nutrition interventions in the treatment of CVD in people with diabetes?,” 21 studies were reviewed. Table 1lists the American Dietetic Association EBNPG recommendations for the prevention and treatment of CVD in people with diabetes.2,11,16
A physically active lifestyle is known to have a key role in health promotion and chronic disease prevention.17 Physical activity is vital to diabetes management,18,19 not only because of its beneficial effects on weight management and blood glucose management, but also because of its role in reducing cardiovascular risk factors and all-cause mortality.20 MNT and aerobic exercise have been shown to reduce blood pressure and improve lipids and are integral components of glucose and weight management.21,22 MNT and aerobic exercise are also predictors of age-specific mortality and cardiovascular event rates.1 Beneficial effects on cardiovascular risk from physical activity are likely to be related to improvements in insulin sensitivity and are independent of weight loss.19
People with diabetes, to reduce their risk of CVD, need at least 150 minutes of moderate-intensity aerobic physical activity per week or at least 90 minutes of vigorous aerobic exercise per week (30–60 minutes on most,or preferably all, days of week), in addition to an increase in daily lifestyle activities, which can include gardening, household work, or even walking breaks during the workday.1
Although increasing evidence links the risk of cardiovascular disease with environmental and psychosocial factors, research is still not conclusive about how it contributes to heart disease risk,23 or how stress management and other forms of psychological intervention for people with heart disease reduce risk for another CVD incident or even help with anxiety or depression.24
An estimated 34.7% of all deaths resulting from cigarette smoking are related to CVD.25 Because cigarette smoking significantly increases the risk for developing atherosclerosis, hypertension, and stroke, and it is the most important preventable cause of premature death in the United States, proper interventions for smoking cessation are necessary.23 Although prevalence of smoking has decreased, people with diabetes are likely to smoke at the same rate as people without diabetes, and physicians do not always provide advice on quitting, as reported by smokers with diabetes.26
There is evidence that psychological smoking cessation interventions are effective in the promotion of abstinence at 1 year.27 Comprehensive tobacco control programs, which include mass media campaigns,can be effective in changing smoking behavior, but their most effective length and intensity has yet to be studied.28
Lifestyle modification is effective in the improvement of many cardiovascular risk factors. According to the American Dietetic Association EBNPG, the strongest recommendations to prevent CVD in people with diabetes are the following:
Cardioprotective nutrition interventions should be implemented in the initial series of encounters and should include reduction in saturated and trans fats and dietary cholesterol and interventions to improve blood pressure; nutrition plans should be individualized to provide a fat intake of 25–35% of total calories, saturated fat and trans fatty acids should be as low as possible and at a maximum of 7% of total calories, and< 200 mg cholesterol per day.
Foods containing 25–30 grams of fiber per day should be included,with special emphasis on soluble fiber sources (7–13 grams).
Plant sterol and stanol ester–enriched foods consumed two or three times per day for a total of 2–3 grams per day may be used in addition to the cardioprotective diet.
Antioxidant supplements (vitamin E, vitamin C, and beta-carotene) have not been observed to reduce risk.
Sodium intake should be limited to ≤ 2,300 mg per day; the Dietary Approaches to Stop Hypertension (DASH) dietary pattern or reduction in sodium to 1,600 mg per day should be recommended after patients adhere to a 2,300-mg sodium limit and do not achieve their treatment goals for reduction in blood pressure.
Intake of at least five to 10 servings of fruits and vegetables per day is recommended.
Ninety to 150 minutes of accumulated moderate-intensity aerobic physical activity per week, as well as resistance training/strength training three times per week, is encouraged.
Raquel Franzini Pereira, MS, RD, LD, is the Health and Wellness Manager at the Minneapolis Heart Institute Foundation in Minneapolis, Minn. Marion J. Franz, MS, RD, LD, CDE, is a nutrition/health consultant, Nutrition Concepts by Franz, Inc., in Minneapolis, Minn.