Читать книгу Practical Carbohydrate Counting - Hope S. Warshaw - Страница 6

CHAPTER ONE
What, Why,
Who, and
How Much?

CARBOHYDRATE COUNTING DEFINED

Carbohydrate Counting is an approach to meal planning that is often considered as two distinct methods with appropriate goals for each: Basic Carbohydrate Counting, a simpler approach, and Advanced Carbohydrate Counting, a progression of skills that entail more complex and time-intensive teaching. However, Basic and Advanced Carbohydrate Counting can also be considered a continuum of a single meal-planning approach, since a person must first master the concepts and skills of Basic Carbohydrate Counting before he or she can progress to Advanced Carbohydrate Counting.

The goals of Basic Carbohydrate Counting are, as expected, relatively minimal and often limited to learning the foods that contain carbohydrate and demonstrating knowledge of how to choose and eat these foods in the proper portions. People using Basic Carbohydrate Counting are encouraged to eat consistent amounts of carbohydrate at meals and snacks at similar times each day, with the end goal of achieving glycemic control and other diabetes and metabolic nutrition goals. Basic Carbohydrate Counting is most appropriate for people with type 2 diabetes who control their diabetes with a healthy eating plan and physical activity, with or without the addition of one or more blood glucose—lowering medications.

The individual goals of Advanced Carbohydrate Counting are more varied and complex, but designed with the overarching objective of helping a person learn to synchronize the amount of glucose-lowering medication they take with the amount of carbohydrate consumed. This method of carbohydrate counting works well with the use of multiple blood glucose—lowering medications (see Appendix II), including oral agents and injectable medications, but is especially suited to multiple daily injection (MDI) insulin regimens or a continuous subcutaneous insulin infusion pump (CSII), commonly known as insulin pump therapy.

People using Advanced Carbohydrate Counting are taught to use customized insulin-to-carbohydrate ratios (ICR) that are calculated based on their individual insulin and carbohydrate needs. They are also taught how to use a customized correction factor (CF), sometimes referred to as insulin sensitivity factor, to correct hyperglycemia and/or prevent further or future hypoglycemia. Ultimately, the use of Advanced Carbohydrate Counting is intended to help people enjoy a more flexible food and medication regimen that is more suited to contemporary daily life while simultaneously achieving improved glycemic control.

Both the Basic and Advanced methods of Carbohydrate Counting are fully described in later chapters.

THE CASE FOR CARBOHYDRATE COUNTING

Carbohydrate counting has grown in popularity as a meal planning approach in the United States since the completion of the Diabetes Complications and Control Trial (DCCT), in which carbohydrate counting was effectively used (Anderson et al. 1993; DCCT 1993). However, carbohydrate counting has been in use internationally since insulin was discovered and has been the meal planning method of choice in the United Kingdom for years (McCulloch et al. 1993).

Carbohydrate Counting has become popular for several reasons. First, the priority of achieving and maintaining glycemic control to decrease morbidity and mortality from diabetes complications has gained greater importance due to the results of the DCCT (DCCT 1993) and the United Kingdom Prospective Diabetes Study (UKPDS) in people with type 2 diabetes (UKPDS 1998). According to the American Diabetes Association’s (ADA) most recent nutrition recommendations and interventions, control of blood glucose to achieve glycemic control is a primary goal of diabetes management (ADA 2008b). Second, more attention is now focused on postprandial blood glucose control (Parkin and Brooks 2002) because of the finding that it is more strongly associated with the risks for atherosclerosis than preprandial blood glucose (Temelkova-Kurktschiev 2000). People with diabetes have defects in insulin action, insulin secretion, or both, and insulin defects impair the regulation of postprandial glucose in response to carbohydrate intake. The quantity and the type/source of carbohydrate intake are the major determinants of postprandial glucose levels (ADA 2008b). Interventions to help people accurately count and control their carbohydrate intake are important to help improve postprandial glycemic control.

The ADA suggests that carbohydrate counting is one method of meal planning that can help people match their doses of some blood glucose—lowering medications, such as insulin and/or insulin secretagogues, to carbohydrate consumption (ADA 2008b). Further, the Dose Adjusted for Normal Eating (DAFNE) trial conducted in Great Britain demonstrated a 1% lowering of A1C in people with type 1 diabetes who received training in adjusting mealtime insulin based on the carbohydrate consumed (DAFNE Study Group 2002).

RECOMMENDATIONS FOR
CARBOHYDRATE CONSUMPTION

Total carbohydrate

The following is a brief review of the current ADA recommendations regarding the consumption of carbohydrate within the framework of a healthy eating plan (ADA 2008b). More extensive reviews can be found (ADA 2008b; Sheard et al. 2004). Regarding the percent of calories that carbohydrate should contribute to the mix of macronutrients, the ADA states that “it is unlikely that one such combination of macronutrients exists that is optimal for all people with diabetes” (ADA 2008b). The ADA recommendations suggest that people seek guidance from the Institute of Medicine’s Dietary Reference Intakes (DRIs) (Institute of Medicine 2002). The DRIs recommend that adults should consume 45–65% of total energy from carbohydrate to meet the body’s daily nutritional needs while minimizing risk for chronic diseases.

The ADA supports the use of either low-carbohydrate or low-fat calorie-restricted diets for short-term use in people with diabetes. For longer term use, the ADA continues to raise questions about the long-term metabolic effects of very low—carbohydrate diets, which eliminate many foods that are important sources of energy, fiber, and other essential nutrients (ADA 2008b). The DRIs indicate that the minimum adult requirement for carbohydrate to provide adequate glucose for the central nervous system without reliance on protein or fat is 130 grams per day (Institute of Medicine 2002; Sheard et al. 2004). The ADA recommends, as do the DRIs, that good health can be achieved with a pattern of food intake that includes carbohydrate from fruits, vegetables, whole grains, legumes, and low-fat milk (ADA 2008b; Institute of Medicine 2002). It is worth noting that contemporary patterns of food intake are often lacking in foods from these groups (U.S. Department of Health and Human Services 2005). The remainder of calories can be contributed by 20–35% from fat and 10–35% from protein (Institute of Medicine 2002).

Amounts and types of carbohydrate

As noted above, the ADA nutrition recommendations suggest that carbohydrate intake, both the quantity and the type or source of carbohydrate, is the major determinant of postprandial glucose levels (ADA 2008b). With this stated, it should be noted that the ADA recommendations now reflect that the use of the Glycemic Index (GI) and Glycemic Load (GL) as a means to assess the glycemic impact of a food on blood glucose can provide a modest additional benefit over that observed when just total carbohydrate is considered (ADA 2008b). The concepts of GI and GL are discussed further in chapter 10, along with other dietary components that impact blood glucose levels, including fiber, polyols, protein, and fat.