Management. Seminar presented at the 2004 CDA Professional Conference, Quebec City, Quebec. Available on CDA web site, DES members section www.diabetes.ca
1.
Calculation for each blood glucose reading To use this method the individual does a pre-meal blood glucose test
subtracts the target blood glucose from the result divides by the correction factor
EXAMPLE:
Current blood glucose level pre-noon = 11.9 mmol/L Target blood glucose level = 7 mmol/L
Correction factor = 2 [one unit of insulin lower glucose by 2 mmol.] (11.9 – 7)/2 = 2.4 units, rounded to 2 units
This amount of insulin will be added to the usual dose or the amount of insulin being taken for the carbohydrate to be eaten at the meal.
2.
Written grid or scale for insulin IDAsUsing this method the educator will create a grid for the client to use based on the
correction factor. The grid indicates the number of units to be added to or subtracted from the base dose.
EXAMPLE:
The TDD is 50 units. 100/50 = 2 [rule method] 1 unit will decrease blood glucose by 2 mmol/L
Dose of rapid or short-acting insulin Intermediate or Long-Acting Insulin
BLOOD GLUCOSE Morning Noon Supper
< 4.0 -1 -1 -1 Lantus 22 units at bedtime
4.1-7.0 6 10 12 TARGET RANGE Usual doses
7.1-9.0 +1 +1 +1
9.1-11.0 +2 +2 +2
11.1-13.0 +3 +3 +3
13.1-15.0 +4 +4 +4
>15.1 +5 +5 +5
For some clients it is necessary to write in the actual dose rather than the amount to be added to the usual dose. In this situation the values in the morning column would read: 5, 6 (usual dose), 7, 8, 9, 10, and 11 respectively.
A line for the usual carbohydrate at the meal A line for the insulin to carbohydrate ratio
Insulin to Carbohydrate Ratio
If a person is planning to eat a variable amount of carbohydrate at meals he can “anticipate” the resulting variability in blood glucose and minimize it by decreasing or increasing the pre- meal dose of short or rapid-acting insulin.
Remember carbohydrate to insulin ratios vary from person to person and may differ from meal to meal. For example, some individuals are more insulin resistant at breakfast than at supper. An insulin resistant person may require 5 gms of CHO per unit of insulin as compared to a thin or fit person or a child needing 20 gms of CHO per unit. Experimenting to get the right ratio requires some time and effort involving frequent blood glucose monitoring and documentation of food intake.
The advantages of using the method are: a. greater flexibility and quality of life b. decreased risk for disordered eating.
c. reflects more normal eating practices where people gauge how much food they are hungry for, rather than a set amount they have to eat.
The disadvantages of this method are:
a. hypoglycemia if the anticipated rise in blood glucose does not occur. Clients should be reminded that a compensatory correction can be safely made at the next meal time. b. weight gain if a person frequently increases insulin to allow for extra food.
NOTE:
Initially, it is suggested that carbohydrate content at meals and snacks remain consistent when first establishing insulin to carbohydrate ratios. Once a baseline is established, greater flexibility and variability of carbohydrate intake will be possible.
There are three methods to determine the insulin to carbohydrate ratio
1. Pattern Management. This method can be used when the amount of insulin taken provides adequate control based on changes in pre versus post-meal blood glucose of no more than 3 mmol/L at 1 hour pc .
Divide the number of grams of carbohydrate taken at a meal by the number of units of insulin given at the meal. The result will yield: 1 unit of insulin per xx grams of
carbohydrate. EXAMPLE
Meal time carbohydrate = 66 grams Meal time insulin = 7 units
66/7 = 9.4
2. Rule of 500
In this method 500 is divided by the TDD
This method will yield the same insulin to carbohydrate ratio for all meals. IDA may be needed based on actual results, observations of “what works” and use of method #1. EXAMPLE
TDD = 63 units
500/63 = 7.9
Therefore, 1 unit of insulin would be taken for every 8 grams of carbohydrate 3. Averages of Pre-meal insulin and carbohydrate intake
In this method:
the bolus or pre-meal insulin doses are added for the full day. the amount of carbohydrate average/day is determined.
the carbohydrate/day is divided by the total pre-meal or bolus insulin. EXAMPLE:
Total pre-meal or bolus insulin/day = 28 units
Average grams of carbohydrate eaten/day = 140 grams 140/28 = 5.0
1.0
Insulin Dose Adjustment for Exercise or Increased Physical
Activity
IDA for exercise or physical activity depends heavily on your client’s response to insulin, the intended activity and its timing in relation to food and insulin. Thus, blood glucose monitoring is required to ensure safe and effective IDA. Physical activity may enhance the effect of exogenous insulin by increasing glucose uptake by muscle cells and intracellular glucose
metabolism. The temporal effect on blood glucose levels will vary depending on the person and intensity and duration of activity. Depletion of glycogen stores may occur with moderate to intense exercise and may result in hypoglycemia many hours after exercise. For some this can be as long as 24 hours. It is important to note that recognition of hypoglycemia may be delayed during vigorous exercise due to the masking of early warning signs.
1.1 Guidelines for
IDAfor exercise are:
a. People with type 1 diabetes who have a urine ketone level > 8.0 mmol/L or blood ketone level > 3.0 mmol/L33 should not exercise. Metabolic deterioration will occur
with exercise.
b. Blood glucose monitoring should be employed initially before, during and after new exercise routines to determine its effect on glycemic levels for the individual. c. Exercise at consistent times of the day will facilitate more reliable IDA.
d. Compensatory food intake may be used to prevent hypoglycemia without IDA or as an adjunct. The client should have a source of short-acting glucose available during exercise. See accompanying table. Adequate hydration is also important.
e. Anticipatory IDA for exercise without compensatory carbohydrate intake may be recommended as follows34. These are guidelines and will need to be evaluated with
each individual.
f. Insulin injection into an exercising limb may speed insulin absorption and action. If possible, Insulin should be injected into a non-exercised part of the body prior to exercise; for example, inject in the abdomen rather the leg before running. g. Following prolonged exercise, subsequent meal doses of rapid or short-acting
insulin may need to be reduced by 20-50%.35
i. IDA may also be needed to the basal insulin dose(s). The bedtime basal insulin may need to be decreased by 10-30% followed prolonged endurance exercise, particularly if this has happened during the evening.
33 2008 Clinical Practice Guidelines, page S48
34 Rabasa-Lohoret R, Bourque J et al. Guidelines for Premeal Insulin Dose Reduction for Postprandial Exercise of Different Intensities and Durations in Type 1 Diabetic Subjects Treated Intensively with Basal-Bolus Insulin Regimens (Ultralente-Lispro). Diabetes Care 2001;24(4):625-630.
35
Jones H. editor. (2009). Building Competency in Diabetes Education: The Essentials. Diabetes
These are only initial conservative recommendations to be evaluated by blood glucose monitoring and revised as necessary.
Exercise Time
Immediately post-meal Morning or Afternoon Very early in morning Post Prolonged activity*Insulin Type
Pre-meal Bolus Morning Basal Previous evening basal Meal or Basal
Intensity of Exercise
Mild
Moderate 20-50%
Strenuous 50%
Prolonged > 3 hours*
Up to 80%
30-50% Adjust with exerciseintensity Trained athletes may
require up to 80% reduction
No more than 50% reduction Adjust with exercise
intensity
Post activity pre-meal doses, may reduce by
20-50%
Bedtime basal insulin, may reduce by 10-30%