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Of course, when viewed from today's world, what those "empowered" patients of Dr. Joslin's time could actually do appears minimal. As in the early days of the modern diabetes management era, however, self-management of nutrition is one area in which patient empowerment is central. Perhaps too much so, many a healthcare provider has lamented, frustrated over seeming lack of adherence by patients! It is the skill to mold a medical nutrition treatment plan to a patient's medical needs and lifestyle patterns that can be the most challenging component of the treatment of diabetes....
The challenge, of course, is to translate scientifically based nutritional recommendations into practical daily eating guidelines. To insist on the ideal would be foolish, as few could follow such recommendations and many would quit in frustration. However, to forget the ideal would forsake the rigor of our treatment goals that patients deserve. The construction of an individualized medical nutrition plan is the science of metabolism blended with the art of perceiving what is realistic for a particular patient, tempered with patience and understanding. It is in this mixed recipe that the optimal balance may be established.
So what is that science? And how do we translate that science into practical education for patients so they can successfully establish and follow a healthy nutritional program? What kind of meal planning approach will work with which patients, and how is that approach determined?
The physiology of adipose tissue and its impact on metabolism is outlined in the previous chapter. This information provides the platform on which those who work with patients approach the nutritional recommendations and support that are important in reaching the therapeutic goals.
For a dietitian, knowledge of the role of adipose tissue and the pullthrough to clinical practice is important and probably has been part of his or her training already. However, for other medical professionals caring for people with diabetes, a level of knowledge in the area of medical nutrition therapy is essential. So intertwined are modern treatment modalities that an understanding of how nutrition prescriptions are designed and how self-care is instructed is essential if any medical professional hopes to optimally utilize current pharmacotherapies of diabetes, dyslipidemia, and hypertension.
Initiation of medical nutrition therapy begins with a realization -- by both the patient and the medical professional -- that the therapy is needed in the first place. Too many patients, once diagnosed, report that they were advised to "avoid sugar" or "cut back on carbs." Whether or not many medical professionals actually are making these simplistic and erroneous suggestions, many patients have the impression that this is the approach their practitioner has advised. Knowing what the ideal nutritional approach may be is insufficient if the nature of such treatment cannot be adequately communicated to the patient.
And the process of emphasizing the importance of medical nutritional therapy is not solely the responsibility of the dietitian or nutritionist. All medical professionals must support the need for a carefully devised nutritional component of treatment. Though this might seem trite or pedantic, it carries even more importance today in this era of polypharmacy.
With all of the newer pharmacologic tools now available, medical nutrition therapy has seemingly been pushed into the background. In truth, new antidiabetes medications can produce near normoglycemia, whereas years ago, sulfonylureas alone might not have succeeded. Further, the adjustable insulin programs offer variations in premeal, rapid-acting insulins to allow variations in food types and quantities.
Nevertheless, a proper medical nutrition program is still quite important from a number of perspectives. Proper adherence to a nutrition program for a person with type 2 diabetes can help reduce the number of medications and the dosage needed to control glucose levels, as well as help ameliorate other related problems such as dyslipidemia and hypertension. In addition, a nutrition program geared toward calorie reduction can help with weight loss, along with improved glycemic control. For those with type 1 diabetes or insulin-treated type 2 diabetes, these issues also apply, but also a proper sense as to the baseline nutritional program allows more systematic -- and thus more accurate -- insulin dose adjustments for variations. Keep in mind, as well, that with excessive food consumption driving excessive insulin doses for coverage, a person with type 1 diabetes can gain considerable weight.
A Clinician's Approach to Medical Nutrition Therapy
A registered dietitian is uniquely qualified to provide medical nutrition therapy (MNT), and is an invaluable member of the patient's healthcare team. The initiation of a medical nutrition therapy program for a patient begins with a thorough patient assessment (addressed later in this chapter).
This assessment should allow the provider to:
- focus on a patient's metabolic needs
- gauge lifestyle patterns
- help set goals
- guide professional intervention and evaluation
From the information gleaned in the assessment process, specific nutrition recommendations can be developed. The current design of medical nutrition therapy for diabetes stems from the recommendations, reviewed below, of a 1994 ADA expert panel. It is the challenge to healthcare providers to translate, initiate, and support these recommendations so that they become practical, individualized nutrition recommendations that are also integrated components of an overall treatment strategy.
Nutrition Therapy Is Not New
Long before insulin was discovered and used as a treatment, diabetes mellitus, which means "the production of great quantities of sweet urine," was described as being a disorder in which one's body was unable to use carbohydrate as fuel. Thus, the logical treatment was to eliminate carbohydrate from the diet. However, as carbohydrate is the body's major energy source, its elimination resulted in the body's utilization of alternative energy sources -- fat and protein. Functionally, the original pre-insulin era treatment for diabetes was marked diet restriction bordering on starvation.
Of course, for those with type 2 diabetes, this approach may not have been so bad, but it did not provide adequate glucose control for many and was not ideal from the perspective of metabolic needs. Carbohydrate is an important stimulus of insulin production by the beta-cells. For people with type 2 diabetes who had developed significant insufficiency of insulin secretory capacity, these early low-carbohydrate diets may have been counterproductive, as they may have understimulated insulin secretion.
As nutrition counseling evolved into the insulin era, the guidelines for carbohydrate intake, then one-third of the daily caloric total, were still insufficient by today's standards. With one-third of the intake as carbohydrate, the remaining intake was about 15% to 20% protein and the remainder was fat. Now, it is known that high saturated-fat diets contribute to dyslipidemias. Over time, we have come to realize that people with diabetes can, and should, handle more carbohydrate. Current recommendations for the percentage of total daily calories that should come from carbohydrate vary, depending on the individual's type of diabetes, metabolic goals and personal lifestyle. For example, an overweight person with type 2 diabetes should aim for approximately 40% of total calories from carbohydrate, whereas, for a lean person with type 1 diabetes 50% to 60% of the total daily calories coming from carbohydrate may be appropriate. Fat content should also be reduced. Currently, the average American consumes about 34% of their daily calories from fat. It has been known for some time now that high- fiber diets are useful, as they provide more bulk, which gives a feeling of "fullness," allowing people to feel satisfied more easily. Fiber also may slow carbohydrate absorption from the bowel. And one type of fiber, called soluble fiber, can help lower blood cholesterol levels.
The Body's Fuel
We have often been told that "we are what we eat." There is considerable truth to this old adage, and it is central to the role of nutrition in the treatment of diabetes and related metabolic disorders. Food consists of three key macronutrients: carbohydrate, protein, and fat.
Carbohydrate is the primary source of fuel for the body. The body can utilize this fuel for immediate needs, or it can store it in the liver and muscle tissue in the form of glycogen for future use. Stored energy provides for varying energy requirements throughout the day and from day to day.
Protein can provide an alternative source of energy if it is needed. However, the major alternative energy source after utilization of stored glycogen is fat, which is also an efficient storage form of energy.
From both the functional standpoint as well as from the nutritional perspective, diabetes can be thought of as being a condition in which there is impairment in the body's ability to use, store, and retrieve these food fuels. The treatment of diabetes focuses on an attempt to correct this impairment.
There are three factors to consider when approaching analysis of a medical nutrition program:
- food quantity
- food types
- timing of food intake
To maintain glucose homeostasis, each of these three components of nutritional therapy must be considered. The proper type of food must get into the body in the proper amount and at the proper time. Doing so allows the available insulin, whether endogenous or exogenous, to be matched in terms of both quantity and time of availability in order to insure proper utilization of the incoming nutrients for immediate energy needs or storage for later use.
Quantity of Food
The measure of food-energy is the calorie (technically, a "kilocalorie," abbreviated "kcal"). The three types of nutrients -- carbohydrate, protein, and fat -- all provide calories, but carbohydrate is the primary source, providing 4 calories per gram. Protein provides a slower, more sustained energy supply, also contributing 4 calories per gram. Protein, however, is better used for functions other than providing energy. Fat, a concentrated energy source, serves as a long-term storage depot for energy. It provides 9 calories per gram.
Basal energy needs differ from person to person, depending on factors such as age, sex, activity level, and body weight.
The preferred method for determining a patient's caloric requirements is to calculate it based on the patient's usual eating style. By conducting a thorough 24-hour recall and food history assessment, a close approximation of the typical intake of calories and grams of carbohydrate, protein and fat can be determined. This level can then be adjusted based on the mutually determined goals of blood glucose control, weight change, and lifestyle.
Alternatively, formulas can be used to approximate the number of calories needed to maintain weight. Once maintenance calories are set, the calories can be adjusted up or down to gain or lose weight.
Another simple method for estimating daily caloric requirements for an average (although somewhat inactive) adult of normal weight would be:
- 25 calories per kilogram (2.2 lbs.) of desirable body weight per day (or 11 calories/lb. of ideal body weight per day) for weight maintenance
- Add 20% to this total if moderately active
- Add 40% to this total if very active
- Add calories if weight gain is desired, or for pregnant (300 calories) or lactating women (500 calories)
The energy needs for children range between 36 and 45 kcal/lb. As children age they need fewer calories. Adolescent boys need 20 to 36 kcal/lb and girls need 15 to 20 kcal/lb, depending on their physical activity.
Adjustments in caloric intake above or below the estimated basal caloric needs can result in weight changes. A caloric intake below basal requirements will lead to the use of non-carbohydrate fuels, ideally fat, leading to weight loss. To gain weight, of course, we must do the opposite. A change of 3500 kcal up or down will result in change in body weight of approximately 1 lb. So, if 25 kcal/kg (11 kcal/lb) body weight represents the caloric level needed to maintain present weight for a person of average activity, then a reduction in that caloric intake by approximately 500 kcal/day can result in weight reduction of about 2 to 4 lbs/month. Losses of slightly more than this -- 4 to 8 lbs/month -- might be appropriate for the most highly motivated individuals, but may not be for an overweight or obese person with type 2 diabetes unless this weight reduction is medically supervised.
Other factors also affect daily caloric needs:
- Women usually require fewer calories than men because they are smaller in size and frame and have less muscle mass.
- Smaller people usually require fewer calories to maintain their weight.
- Younger, more active people need more calories than older people, especially during periods of growth.
- Caloric needs increase with some types of physical stress, such as after severe injury or illness or during pregnancy and lactation.
The additional fuel needed to power physical activity increases caloric needs. While an active lifestyle requires more calories, it does not require more insulin than that which would be required to maintain glucose control if less activity were performed. Though active people with diabetes, in order to maintain current body weight, could eat additional food to fuel increased activity and continue to take the same insulin doses as if they were less active, the better course would be to adjust their insulin.
Suggested Reading
Standards of Medical Care in Diabetes–2007, American Diabetes Association Diabetes Care 2007 30: S4-41 (Updated annually -- seek newest version)
Diagnosis and Classification of Diabetes Mellitus, American Diabetes Association Diabetes Care 2007 30: S42-47 (Updated annually -- seek newest version)
Diabetes Epidemiology: Collaborative Analysis of Diagnostic Criteria in Europe (DECODE). Lancet 1999; 354:617–621.
Tominaga M, et al. The Funagata Diabetes Study. Diabetes Care 1999; 22:920–924.
The DECODE study group. Glucose tolerance and mortality: comparison of WHO and American Diabetes Association diagnostic criteria. Lancet 1999; 254: 617–621.
Copyright © 2010 by Joslin Diabetes Center. All rights reserved. Reprinted with permission. Neither this book nor any part thereof may be reproduced or distributed in any form or by any means without permission in writing from Joslin. Note: Joslin does not endorse products or services.
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Please Note: Reasonable measures have been taken to ensure the accuracy of the information presented herein. However, drug information may change at any time and without notice and all readers are cautioned to consult the manufacturer's packaging inserts before prescribing medication. Joslin Diabetes Center cannot ensure the safety or efficacy of any product described in this book.
Professionals must use their own professional medical judgment, training and experience and should not rely solely on the information provided in this book to make recommendations to patients with regard to nutrition or exercise or to prescribe medications.
This book is not intended to encourage the treatment of illness, disease or any other medical problem by the layperson. Any application of the recommendations set forth in the following pages is at the reader's discretion and sole risk. Laypersons are strongly advised to consult a physician or other healthcare professional before altering or undertaking any exercise or nutritional program or before taking any medication referred to in this book.
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