Medical Nutrition Therapy for Diabetes

The insulin dose depends on basal needs, food intake (especially the total amount of carbohydrate) and amount of physical activity. Changes in the dose of rapid- or short-acting insulin can be made  according to a sliding scale that increases the dose for higher blood glucose levels and decreases the dose when blood glucose levels are lower. In addition, average blood glucose levels at various times of day can be calculated to further adjust the insulin recommended (rapid, short, intermediate and/or long- acting preparations).

Self-blood glucose testing is recommended before each meal and the bedtime snack to help assess the dose and make changes as needed. Testing at 2:00-3:00 am is useful for evaluating night-time hypoglycemia and fasting hyperglycemia (dawn phenomenon).

A variety of blood glucose testing meters are available. Many contain memory to store the date, times and test results. Some can be downloaded to personal computers that graphically display blood glucose readings. New meters are available that allow the user to obtain blood from other areas beside the fingertips.

Average blood glucose levels over the last 3 months are measured by a blood test called glycated hemoglobin. Different assays are available, each with their own normal (nondiabetic) range; hemoglobin A1c (HbA1c) is the preferred method. It is recommended to use the same laboratory to avoid confusion. The teen should have the test performed before visiting the physician to facilitate early discussion of results and if necessary, strategies to improve control. The 1994 Diabetes Control and Complications Trial (DCCT) that included 195 adolescents (13-18 years old) demonstrated that

better blood glucose control significantly reduced the risk for long-term complications.5 Based upon

the DCCT results, the target HbA1c is 7%.

Medical Nutrition Therapy

Food intake influences the amount of insulin required to meet blood glucose target goals. Dietary carbohydrate influences postprandial blood glucose levels the most and is the major determinant of meal-related insulin requirements. The intermediate- or longer-acting insulin usually covers the effects of protein and fat.

At diagnosis, the teen and the family are taught how to monitor food intake with basic carbohydrate- counting guidelines (see Table 6 for teaching ideas). Two types of counting methods are available to monitor carbohydrate intake.

•         Counting carbohydrate servings: Standard servings of foods in the starch/bread, fruit and milk groups are considered to be approximately equal in carbohydrate value (1 serving = approximately 15 g carbohydrate). Carbohydrate values are obtained from food lists and nutrition labels. For example, a teen who eats 2 pieces of toast (2 carbs) with margarine and 1 cup of milk (1 carb) for breakfast is eating a 3 carb breakfast. If premeal insulin is calculated on the basis of units of short- acting insulin per carb and the teen’s dose is 1 unit/1 carb, the insulin dose would be 3 units to cover the carbohydrate in this breakfast.

•         Counting grams of carbohydrate: The specific carbohydrate gram value for all foods eaten is determined, thus increasing the accuracy of the carbohydrate count. For example, the above breakfast is equal to approximately 45 g carbohydrate (3 carbohydrate servings x 15 g/serving = 45 g total carbohydrate). However, if the bread is actually 20 g/slice and the milk is 12 g/cup, the carbohydrate intake is 52 g. If the same teen is taking 1 unit/15 g carbohydrate, the insulin dose would be 3.5 units for this breakfast instead of 3 units.

TABLE 6

Teaching Ideas for Carbohydrate-Counting

Use food models to illustrate portion sizes. Provide opportunities to weigh and measure

common foods.

Teach how to read nutrition labels with labels from actual food items.

Plan sample menus that incorporate school lunches, snacks from vending machines, and fast food menu items.

Teach how to work-in sugar-containing foods in moderation.

Carbohydrate counting guidelines are provided by a stepped approach (see Table 7). With conventional insulin therapy, a structured meal plan with defined carbohydrate goals is necessary to synchronize the timing of carbohydrate intake with the time-action of the insulin used and to promote a consistent intake of dietary carbohydrate. Once teens are comfortable with the basics and learn how to identify blood glucose patterns, they may choose to begin a more intensive insulin regimen. At this level carbohydrate/insulin ratios and corrective dose adjustments are used to increase flexibility with the timing of meals and snacks and the amount of carbohydrate eaten. Carbohydrate counting as a meal planning approach offers varied food choices and many strategies for achieving target blood

glucose levels.6

TABLE 7

Carbohydrate Counting Guidelines Level 1 – Basic Carbohydrate Counting

Objective:   To identify usual carbohydrate (CHO) intake and promote consistent CHO at meals and snacks.

•      Why CHO relates to blood glucose levels.

•      Importance of consistent amounts of CHO at meals and snacks.

•      Which foods contain CHO, protein and fat.

•      How to identify portion sizes of common foods.

•      How to read nutrition labels to determine number of CHO choices.

Level 2 – Advanced Carbohydrate Counting

Objectives

1.     To learn how to identify patterns in blood glucose levels that relate to insulin, food intake and/or exercise and make changes to improve blood glucose levels.

•      Importance of monitoring blood glucose levels.

•      How to identify blood glucose patterns.

•      How to adjust insulin, food and/or exercise to reduce high and/or low blood glucose levels.

•      Suggestions to help avoid unwanted weight gain.

•      Suggestions for treating low blood glucose episodes.

2.     To learn how to adjust rapid- or short-acting acting insulin when CHO intake and timing of meals and snacks vary.

•      How to calculate the amount of insulin needed to cover the amount of CHO eaten.

•      How to determine the amount of insulin needed to lower your blood glucose level.

•      Importance of accurate CHO counting.

•      How to make insulin adjustments for high fat meals, high fiber foods and unusually large amounts of CHO or protein.

TO BE CONTINEU


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