Clinicians providing nutrition therapy should complete a nutrition assessment, and provide tailored education and counseling based on the individual needs of the person with diabetes. While many standardized meal plans and menus are available in print or Web-based, it is through the collaborative development of individualized nutrition interventions with ongoing support for behavior change that best facilitates achievement of patients' health goals (Evert, 2014). Nutrition education should be delivered by health professionals with appropriate training, knowledge and skills, and of sufficient duration and quality to meet patients' needs effectively (Miller, 2002).
Goals and eating patterns
Goals of nutrition therapy for diabetes promote healthful eating patterns designed to lower glucose, blood pressure, and alter lipid profiles to lower cardiovascular risk factors, emphasizing a variety of nutrient-dense foods in appropriate portion sizes to improve overall health (Evert, 2014). Eating patterns or dietary patterns are combinations of different foods or food groups that characterize relationships between nutrition and healthy promotion or disease prevention. Eating patterns include Mediterranean-style, DASH, vegetarian or vegan, low carbohydrate and low fat. Eating plans should take into account individual personal and cultural preferences, health literacy and numeracy, willingness to change behaviors and metabolic goals. Major metabolic goals are to attain individualized glycemic, blood pressure and lipid goals, and achieve and maintain body weight goals to delay and prevent complications of diabetes (Evert, 2014).
A recent systematic review provides evidence that modifying the amount of macronutrients can improve glycemic control, weight and lipids in people with diabetes. Low-carbohydrate, low-glycemic index (GI), Mediterranean and high-protein diets reduced hemoglobin A1c by 0.12-0.5% compared to comparison or control diets. These hemoglobin A1c reductions were significant, with a reduction of 0.5% that was similar to that achieved by using medication and associated with lower risk of microvascular complications (Ajala, 2013). However, while other various meta-analysis and systematic reviews have been conducted, there is no conclusive evidence regarding an ideal macronutrient distribution for all people with diabetes (Evert, 2014). Another recent systematic review found there is no ideal mix of macronutrients that can be applied and that macronutrient proportions should be individualized (Wheeler, 2012).
Meal planning approaches
There are multiple meal planning approaches that can be used as effective nutrition interventions. Examples include carbohydrate counting, simplified healthful food choices (i.e., the Plate Method), and individualized meal plans based on percentages of macronutrients, exchange lists or glycemic index. For individuals using fixed daily insulin doses, consistent carbohydrate intake with respect to time and amount can reduce risk of hypoglycemia and improve glycemic control (Evert, 2014).
There is insufficient evidence to recommend a specific amount of carbohydrate intake for all people with diabetes. Despite the conflicting evidence evaluating the effect of differing percentages of carbohydrates, monitoring carbohydrates remains a useful strategy. The quantity and the type of carbohydrate in a food influence blood glucose level, and the total amount of carbohydrate is the primary predictor of glycemic response. Therefore, the effect of the amount of carbohydrates and available insulin on postprandial blood glucose should be considered in developing a meal plan. Monitoring carbohydrate intake, either by carbohydrate counting or experience-based estimation, remains a key strategy in achieving glycemic control (Evert, 2014).
It has been demonstrated that the substitution of sucrose for starch for up to 35% of calories may not affect glycemia or lipid levels. Since foods high in sucrose are high in calories, substitution should be made to ensure nutrient density of overall eating pattern. There is evidence from studies of individuals without diabetes that because of rapidly absorbable carbohydrates (such as sucrose or high-fructose corn syrup) large quantities of sugar-sweetened beverages (SSBs) should be avoided to lower risk of weight gain and worsening of cardiometabolic risk factors (Evert, 2014).
People with diabetes should consume at least the amount of fiber and whole grain recommended for the general population. Encourage consuming a wide variety of fiber-containing foods such as legumes, fiber-rich cereals, fruits, vegetables and whole grain products to achieve fiber intake goals of 14 g/1,000 calories or about 25 g/day for adult women and 38 g/day for adult men, and meet recommendations to consume at least half of all grains as whole grains (Evert, 2014).
A recent systematic review on low-glycemic index diets concluded a low-GI diet can decrease HgbA1c by 0.5%, which was statistically significant (Thomas, 2009). Substituting low-glycemic load foods for higher-glycemic load foods may modestly improve glycemia. The ADA nutrition guideline states the evidence evaluating the effect of glycemic index or glycemic load is complex and often difficult to discern the independent effect of fiber compared to that of glycemic index on glycemic control or other outcomes (Evert, 2014). With a lack of a standard definition of a low-glycemic food and different responses in individuals, it is difficult to teach this method to patients. Consideration of glycemic effects of a mixed meal makes it even more difficult to include this in meal planning, especially for those patients with numeracy concerns. Patients who already are competent carbohydrate gram counters perhaps best utilize use of glycemic index or load food lists.
There is little evidence that use of non-nutritive sweeteners (NNSs) leads to reduction in body weight. If NNSs are used to replace caloric sweeteners without caloric compensation, then NSSs may be useful in reducing caloric and carbohydrate intake (Wiebe, 2011).
For people with diabetes and no evidence of diabetic kidney disease, evidence is inconclusive to recommend an ideal amount of protein intake for optimizing glycemic control or improving one or more CVD risk measure. While some randomized control trials have compared the effect of higher protein diets to usual intake on diabetes outcomes, they have been small and of short duration. For people with diabetic kidney disease, reducing the amount of protein below usual intake is not recommended because it does not alter glycemic measures, cardiovascular risk measures or the course of glomular filtration rate (GFR) decline. Protein appears to increase insulin response without increasing plasma concentrations, therefore carbohydrate sources high in protein should not be used to treat hypoglycemia (Evert, 2014).
Evidence is inconclusive for an ideal amount of total fat intake, so fat goals should be individualized to be consistent with goals to either maintain or lose weight. The Institute of Medicine recommendations define acceptable macronutrient distribution for total fat as 20-35% of calories. The type of fatty acids consumed is more important than the total dietary fat in supporting metabolic goals and influencing risk of cardiovascular disease (Evert, 2014). The 2013 AHA/ACC Lifestyle Management to Reduce Cardiovascular Risk guideline recommends reduce percent of calories from saturated fat to 5-6% (Stone, 2014).
Monounsaturated fatty acids (MUFA)
The Mediterranean-style mono-unsaturated fatty acid-rich eating pattern is associated with improved glycemic control and reduction in cardiovascular risk factors, and can be utilized as an effective alternative to lower-fat, higher-carbohydrate eating patterns. Studies demonstrated improvements when MUFA (monounsaturated fatty acids) was substituted for carbohydrates and/or saturated fats, but some of the studies included a caloric restriction, which may have contributed to positive outcomes (Evert, 2014). A recent randomized trial, the PREDIMED trial, enrolled subjects with either T2DM or at least three CVD risk factors. The authors concluded an energy-unrestricted Mediterranean diet, supplemented by either extra-virgin olive oil or nuts, resulted in a substantial reduction in the risk of major cardiovascular events among high-risk persons and supported the benefits of the Mediterranean diet for the primary prevention of cardiovascular disease (Estruch, 2013).
An increase in foods containing Omega-3 fatty acids (EPA and DHA from fatty fish) and ALA is recommended because of beneficial effects on lipoproteins, and prevention of heart disease and associations with positive outcomes in observational studies. Evidence does not support recommending omega-3 supplements for the prevention or treatment of cardiovascular events (Evert, 2014).
A systematic review of randomized control trials showed that decreasing sodium intake reduces blood pressure in people with diabetes (Suckling, 2010). The Institute of Medicine report suggested there is no evidence on health outcomes to treat certain population subgroups – including people with diabetes – differently than the U.S. population in regards to the amount of salt reduction (Institute of Medicine, 2013).
If one chooses to drink alcohol and has not been cautioned against it, limit intake to one drink per day for women and two drinks per day for men, according to USDA guidelines. A drink is defined as 12 oz. of regular beer, 5 oz. of wine, or 1.5 oz. of 80-proof distilled spirits. To reduce the risk of hypoglycemia, alcohol should be consumed with food, especially if taking insulin or insulin secretagogues.