American Diabetes Association Guide to Nutrition Therapy for Diabetes. Marion J. Franz

1995). Improvements were maintained to 3 years without increasing the risk of hypoglycemia (Sämann 2005). A similar program in Australia teaching carbohydrate counting and insulin dose adjustment to patients with type 1 or type 2 diabetes and taught by dietitians and doctors also prompted good results. Participants reported A1C levels fell from 8.7% initially to 8.1% at 12 months (Lowe 2008).

      The role of nutrition behaviors in achieving glycemic control in 623 intensively treated patients in the Diabetes Control and Complications Trial (DCCT) was examined. The four nutrition behaviors associated with a clinically significant reduction in A1C (0.9%) were as follows: adhering to the prescribed meal and snack plan, adjusting insulin dose in response to meal size, promptly treating hyperglycemia, and avoiding overtreatment of hypoglycemia (Delahanty 1993).

      Nutrition Therapy Clinical Effectiveness Studies

      Nutrition therapy for diabetes is clinically effective. Randomized controlled trials and observational outcome studies have documented decreases in A1C of ~1–2% (range –0.5% to –2.6%), depending on the type and duration of diabetes. These outcomes are similar to those from oral glucose-lowering medications.

      Although attempts are often made to identify one approach to diabetes MNT, a single approach does not exist. Research shows that there are many types of nutrition interventions that are effective. Interventions include reduced energy/fat intake, carbohydrate counting, simplified meal plans, healthy food choices, individualized meal-planning strategies, exchange choices, use of insulin-to-carbohydrate ratios, physical activity, and behavioral strategies. In reviewing consistent themes for nutrition intervention, it appears that, for individuals with type 2 diabetes, reducing the energy content of usual food intake is central to successful outcomes. For individuals with type 1 diabetes, adjusting insulin doses for planned carbohydrate intake is of primary importance.

      Central to these interventions are multiple encounters to provide education and counseling initially and on a continued basis. The number and duration of MNT encounters may need to be greater if the patient has language, ethnic, or cultural concerns; if changes in medications (such as addition of glucose-lowering medications or insulin therapy in type 2 diabetes or changes in insulin regimens in type 1 or type 2 diabetes) are made; or for weight management. Nutrition education and counseling must be sensitive to the personal needs and cultural preferences of the individual and his or her ability and willingness to make changes.

      At ~6 weeks after the initial nutrition encounter, it should be determined whether the individual is making progress toward personal goals. If there is no evidence of progress, the individual and nutrition professional need to reassess and consider possible revisions to the nutrition care plan. At 3 months, changes in medical therapy (medications added or adjusted) need to be made if blood glucose concentrations or A1C percentages have not shown a downward trend; the patient has lost weight with no improvement in glucose; the patient is doing well with lifestyle changes and further interventions are unlikely to improve medical outcomes; or if the patient has done all that he or she can or is willing to do.

      How often nutrition education and counseling needs to be implemented is unknown at this time. Evaluating the effectiveness of diabetes MNT is performed at 3, 6, or 12 months and usually includes the initial series of encounters. The number of initial and follow-up sessions varies in all the studies. It can be speculated that just as it is important for individuals with diabetes to be seen on a regular basis for medical care, it is also important for individuals to receive continuing education, counseling, and support for lifestyle changes. The Academy of Nutrition and Dietetics nutrition practice guidelines for type 1 and type 2 diabetes recommends at least one follow-up encounter annually to reinforce lifestyle changes and to evaluate and monitor outcomes that affect the need for changes in MNT (or medication) (Acad Nutr Diet 2008a). For example, children and adolescents often require MNT changes because of growth or other lifestyle factors. Patients with type 2 diabetes often require the addition of or changes in medication. The RD can also assist physicians and other health care providers by helping patients understand and accept the reasons for management changes.

      Other important clinical outcomes that need to be evaluated, in addition to A1C levels, are lipids and blood pressure. In studies done primarily in individuals without diabetes, cardioprotective nutrition therapy implemented by RDs resulted in a reduction of serum total cholesterol by 7 to 21%, LDL cholesterol by 17 to 22%, and triglycerides 11 to 31% (Acad Nutr Diet 2011). Pharmacological therapy changes should be considered if goals are not achieved between 3 and 6 months after initiating MNT.

      Nutrition therapy is also effective in reducing blood pressure in both normotensive and hypertensive adults. Substantial reductions in blood pressure that are clinically relevant are reported from implementation of multiple lifestyle interventions (Appel 2006). Nutrition therapy recommendations (weight loss, sodium reduction, increased physical activity, and following the DASH diet [Dietary Approaches to Stop Hypertension] [rich in fruits, vegetables, and low-fat dairy products but low in saturated and total fat]) in hypertensive individuals not on medication reduced systolic blood pressure by 14.2 mmHg and diastolic blood pressure by 7.4 mmHg and in nonhypertensive individuals reduced systolic blood pressure by 9.2 mmHg and diastolic blood pressure by 5.8 mmHg (Appel 2003). However, generally, studies implementing MNT for hypertension implemented by RDs report an average reduction in blood pressure of ~5 mmHg in both systolic and diastolic blood pressure (Acad Nutr Diet 2008b).

SUMMARY

      • For individuals with type 2 diabetes, attention to food intake and patterns of eating are important for the management of diabetes, even if on medications, including insulin.

      • For individuals with type 1 diabetes, matching insulin doses to planned carbohydrate intake is important for the management of diabetes.

      • Nutrition education and counseling is best provided in a series of encounters—usually one initial encounter with two or three follow-up encounters, which can be implemented individually or in groups. The dietitian (or nutritionist) should determine if and when additional encounters are needed.

      • Ongoing nutrition education and counseling is needed yearly, or more often as required or requested, or when changes in medication are made.

      • A variety of nutrition interventions can be implemented depending on which are best suited to the needs of the individual patient. For patients with type 2 diabetes, the focus should be on reducing or maintaining a reduced energy intake. For patients with type 1 diabetes, a primary focus for educating patients is on how to adjust insulin doses on the basis of planned carbohydrate intake.

      • Blood glucose monitoring and A1C results can be used to evaluate the effectiveness of MNT; lipids and blood pressure outcomes also require monitoring and evaluation.

      • To successfully integrate MNT into overall diabetes management, an interdisciplinary team approach is essential.

      BIBLIOGRAPHY

      Academy of Nutrition and Dietetics: Disorders of lipid metabolism evidence-based nutrition practice guideline, 2011. Available from http://www.adaevidencelibrary.com/topic.cfm?cat=4528. Accessed 5 June 2011

      Academy of Nutrition and Dietetics: Effectiveness of MNT for hypertension, 2008b. Available from http://www.adaevidencelibrary.com/conclusion.cfm?conclusion_statement_id=251204. Accessed 5 June 2011

      Academy of Nutrition and Dietetics: Type 1 and type 2 diabetes evidence-based nutrition practice guidelines for adults, 2008a. Available from http://adaevidencelibrary.com/topic.cfm?cat=3253. Accessed 5 June 2011

      Andrews RC, Cooper AR, Montgomery AA, Norcross AJ, Peters TJ, Sharp DJ, Jackson N, Fitzsimons K, Bright J, Coulman K, England CY, Gorton J, McLenaghan A, Paxton E, Polet A, Thompson C, Dayan CM: Diet or diet plus physical activity versus usual care in patients with newly diagnosed type 2 diabetes: the Early ACTID randomized controlled trial. Lancet 378:129–139, 2011