Nutrition Connection: Diabetes Management and Carb Counting

(reprinted from Dietary Manager, July/August 2010)

Diabetes is a group of disorders in which the body cannot regulate the amount of glucose in the blood.  There are three broad categories of diabetes: type 1, type 2, and gestational diabetes.  Prediabetes is a condition in which individuals have blood glucose levels higher than normal, but not high enough to be classified as diabetes.  Roughly 8 percent of the U.S. population has diabetes, although about one third of them are undiagnosed. About 30 percent of adults aged 20-59 years and over 35 percent of adults aged 60 and older have prediabetes.

The prevalence of diabetes in the U.S. has doubled since 1994, and it is the seventh leading cause of death among all races. Approximately 24 percent of nursing home residents have diabetes.  Medical costs to treat prediabetes and diabetes (diagnosed and undiagnosed) are estimated to be over $150 billion per year, and indirect costs of disability and premature death are estimated to exceed $60 billion per year. 

Poorly controlled blood glucose levels are associated with long-term complications affecting the eyes, kidney, nervous system, vascular system, and heart.  Diabetes is the leading cause of blindness in working-aged adults in the United States. It is also the leading cause of end stage renal disease and nontraumatic limb amputation.  The risk of death from heart disease and stroke are two to four times higher among adults with diabetes.  Tight control of blood glucose levels is associated with reduced risk for or delayed onset of these complications.

Carbohydrate Metabolism
In a healthy person, blood glucose level is regulated by the interaction of several hormones, including insulin. Insulin allows glucose to move from the blood into the liver, muscle and fat cells where it is used for fuel. In type 1 diabetes, the pancreas is unable to produce adequate amounts of insulin. Type 1 is more commonly seen in children and young adults than older adults. It used to be called juvenile-onset diabetes or insulin-dependent diabetes. These names are no longer used because type 1 can occur in adults of all ages and insulin may be required for individuals who were originally diagnosed with type 2 diabetes. Type 1 diabetes can occur in adults due to the destruction of the pancreas by alcohol, disease, or removal by surgery. It can also result from progressive failure of the pancreatic cells to produce insulin. Individuals with type 1 diabetes require daily insulin injections to sustain life. Diet is a vital part of disease management to maintain desirable blood glucose levels and to delay long-term complications.

In type 2 diabetes, the cells cannot use insulin properly.  The pancreas secretes insulin, but the body is partially or completely unable to use it, resulting in insulin resistance.  The body responds by secreting more and more insulin.  In time, the pancreas may lose the ability to produce sufficient insulin or fail to produce any insulin.  Type 2 diabetes used to be called adult-onset diabetes or non-insulin dependent diabetes. These names are no longer used because type 2 diabetes occurs in children, teens, and young adults.  Also, some patients with type 2 diabetes need to use insulin to control blood glucose levels. 

Risk Factors for Diabetes
Experts estimate that at least 90 percent of patients with diabetes have type 2. Risk factors include:

• Family history of diabetes
• Ethnicity
• Age 45 yrs+
• History of gestational diabetes
• History of prediabetes
• Overweight (BMI> 25),
• High blood pressure
• Abnormal blood lipid values
• Physical inactivity or sedentary lifestyles

The genetic links associated with diabetes are complex. However, the problems seen in type 2 diabetes occur when a diabetogenic lifestyle (excessive energy intake, inadequate energy expenditure resulting in obesity) is superimposed upon certain genetic traits. Race is also a factor. African Americans, Native Americans, Hispanic and non-Hispanic blacks have a much higher prevalence of type 2 diabetes than non-Hispanic white and Asian populations. It is slightly more common in older women than men. Some medications, especially glucocorticoids, can antagonize insulin use by cells.

Diagnosis of Diabetes
Standards of Medical Care in Diabetes are published by the American Diabetes Association that establishes national standards for desirable blood glucose ranges and diagnostic criteria for physicians to diagnose prediabetes and diabetes. Initially, a fasting blood glucose test is done as part of an annual physical exam. Normal fasting blood glucose values are < 100 mg/dL. If the fasting level is > 126 mg/dL, more blood tests are needed to confirm the diagnosis of diabetes. If the fasting blood glucose test result is > 100 mg/dL but < 126 mg/dL, more tests may be ordered or prediabetes is diagnosed. Infections, inflammation, injury, illness, acute medical problems, emotional stress, and some medications can cause blood glucose levels to the elevated temporarily.

The ‘gold standard’ test used to confirm a diagnosis of diabetes is the oral glucose tolerance test. This test requires the patient to consume a 75 gm carbohydrate beverage following an 8 hour fast. Blood samples are taken at set time intervals. This is a costly and draining test for most patients, especially older adults.

The 2010 Standards of Medical Care in Diabetes have added Hemoglobin A1c (HbA1c) as an additional tool to diagnose new cases of type 1 or type 2 diabetes. It is not a useful measure to diagnose gestational diabetes. HbA1c is a measure of average glucose control. This test measures the percentage of hemoglobin molecules bound to glucose. Hemoglobin is carried by red blood cells which have an average life span of 120 days. Glucose remains bound to hemoglobin for the life of the cell. Once the cell dies, the glucose is released back into the blood stream. The higher the average blood glucose levels, the higher the percentage HbA1c.  In healthy adults, HbA1c is between 4-6 percent. The diagnostic criterion for diabetes using HbA1c is > 6.5 percent. This test is also used to monitor dietary compliance and long term glucose control. Good diabetic control is defined as 7 percent or less.

Management of Diabetes
Blood glucose control is the foundation of treatment for all types of diabetes. Type 1 diabetes is managed with daily insulin injections and diet.  Type 2 diabetes is usually controlled with diet, weight loss, exercise, and oral medications.

The relationships between diet and symptoms of hypoglycemia or hyperglycemia have been recognized since ancient times. Before insulin was discovered, diet was the only way to manage diabetes.  In the late 1850s, French physicians recommended consumption of large quantities of sugar as the dietary treatment of diabetes.  However, during the Franco-Prussian War (1870s), French physicians noted the disappearance of glycosuria in diabetic patients during rationing of food.  Based on this observation (limited food = better diabetes control), the idea of individualized diets to treat diabetes was formulated.  In the early 20th century, very precise diets were developed in hopes of controlling diabetes. The focus of the diet was low carbohydrate (20 percent of calories), moderate protein (10 percent of calories), and very high fat (70+ percent of calories). Some of the diets were very low in energy; 500-800 calories/day. There were many ‘fad diets’ such as the ‘oat-cure diet’, ‘milk diet’, ‘rice diet’, but none of them managed blood glucose effectively. Selected individuals found that these limited diet plans were successful, but many patients died a few years after the onset of symptoms from vascular complications of diabetes or infections.  Once insulin was discovered, scientists thought they had ‘cured’ diabetes. However, insulin is only part of the treatment for type 1 diabetes and not needed for many with type 2 diabetes.

Diet continues to be the cornerstone of the diabetes treatment plan. In the 1950s the American Diabetes Association, in conjunction with the US Public Health Service, developed the ‘exchange system’. This plan grouped foods of similar macronutrient (carbohydrate, protein and fat) density into groups or exchanges.  Diets consisted of a pattern of exchanges for each meal and snack. The patient would select food choices from the different exchange groups. Early forms of the exchange system were rigid and food groups had limited choices.  ADA Diet Plans based on calorie level were mass produced.  Some readers may remember multiple ADA Diets (1200 Kcal, 1500 Kcal, 1800 Kcal etc.) served on the healthcare facility menu.  The complexity of writing the diets and the precision required to correctly serve the diet pattern made the system difficult to follow. ‘Not serving therapeutic diets as ordered’ was a frequent deficiency noted by surveyors. 

Research has demonstrated that the amount of carbohydrate eaten affects your blood glucose level more than anything else in the diet. For most patients/residents, the best diet is one consisting of modifying the foods that they are currently eating. Attempts to calibrate a precise macronutrient composition of the diet to control diabetes are generally not supported by the research. For patients with type 2 diabetes, weight management is key and energy restriction may be needed. Second to restricting energy is consistent carbohydrate intake throughout the day. 

Food sources of carbohydrate come in three forms.

• Starch -- found in bread, pasta, cereals, grains, potatoes, beans, peas, lentils, and corn
• Sugar -- found naturally in fruits, milk, and yogurt
• Added Sugar – found in desserts, candy, jams, syrups, and sweetened food products (i.e., cereals, yogurt, beverages, and baked goods)

The American Diabetes Association recommends a Consistent Carbohydrate Diet for patients in an acute care setting. The American Dietetic Association recommends either a Consistent Carbohydrate Diet or liberalized Regular Diet with consistent mealtimes and carbohydrate intake for residents in long term care. The Consistent Carbohydrate Diet does not have a specific calorie level, but is based on a specific amount of carbohydrate served at each meal. The carbohydrate distribution is the same each day.  Some individuals may require energy restriction to achieve or maintain desirable weight.

Carbohydrate Counting is a simpler, more flexible method of managing diabetes with diet than the traditional exchange system.  Carbohydrate is the primary nutrient affecting blood glucose and insulin levels after a meal or snack.  For most adults, dietary carbohydrates in foods affect blood glucose approximately the same when eaten in similar amounts.  The Carbohydrate Counting method combines the fruit, starch and milk exchanges into one group. All single servings contain 15 gm of carbohydrate and are counted as one ‘carb’ serving. Meal plans include a specific number of ‘carb’ servings for each meal and snack.

Table 1. Carbohydrate Counting

Carbohydrate Counting is different from the traditional exchange system in that the pattern of food exchanges per meal may vary from day to day. Under the traditional exchange system, the meal pattern for lunch might include 1 milk exchange, 1 fruit exchange, and two starch exchanges every day for a total of 60 gm of carbohydrate. Using the Carbohydrate Counting system, the meal pattern could vary as long as the meal provided 60 gm of carbohydrate.  Some options might include 2 fruit servings and 2 starch servings or 1 milk serving and 3 starch servings for a total of 60 gm of carbohydrate.

It is important to note that a healthy diet contains food from each of the exchange groups. Some patients/residents may experience higher blood glucose levels after consuming certain carbohydrates, especially fruit juices at breakfast.

Implications for Practice
There is no ‘cookie cutter’ approach to managing diabetes. CDMs must work collaboratively with RDs to determine if patients/residents can control their diabetes and weight using a liberalized Regular Diet or a Consistent Carbohydrate Diet. Using the Carbohydrate Counting method will give more flexibility to the menu and more choices of food combinations to meet the prescribed carbohydrate levels.

References:
American Diabetes Association, Standards of Medical Care in Diabetes- 2009. Diabetes Care. 32(Sup 1) S13-S61.
American Diabetes Association, Standards of Medical Care in Diabetes- 2010. Diabetes Care. 33(Sup 1) S11-S61.
Full Accounting of Diabetes and Pre-Diabetes in the U.S. population in 1988-1994 and 2005-2006, Cowie, C. et al. Diabetes Care, 2008 Feb; 32(2):287-294.
Xu J, Kochanek KD, Tejada-Vera B. Deaths: Preliminary data for 2007. National vital statistics reports; vol 58 no 1. Hyattsville, MD: National Center for Health Statistics. 2009. http://www.cdc.gov/nchs/data/nvsr/nvsr58/nvsr58_01.pdf
WHO, 2009, Diabetes http://www.who.int/mediacentre/factsheets/fs312/en/

By Mary D. Litchford, PhD, RD, LDN

Mary D. Litchford, PhD, RD, LDN is a nationally-recognized speaker and the author of various articles and books, including Common Denominators of Declining Nutritional Status.