The blood sugar is controlled by hormones. One of these is insulin, which is secreted by the pancreas in response to rising blood sugar. People with diabetes either can't make their own insulin or don't have enough for the body's needs. In either case, replacement or supplemental insulin is necessary.
Basal Insulin
The right amount of insulin is critical to prevent blood sugar from going too low or getting too high. The dose is calculated based on the daily amount of food and exercise for each individual. About 40 to 50 percent of the total daily insulin dose is to replace insulin overnight, when fasting and between meals. This is called the basal insulin replacement -- and the dose usually stays the same from day to day.
Bolus Insulin
The remaining insulin, called the bolus insulin replacement, is to cover carbohydrates in the diet and to correct high blood sugar. The bolus insulin dose varies. Bolus insulin is calculated as a ratio of insulin to carbohydrate; 1 unit of rapid acting insulin will dispose of 12 to 15 g of carbohydrate. If you are more or less sensitive to insulin, you may need to increase or decrease the dose. One unit of insulin drops the blood glucose by 50 mg/dL, but this can also vary according to insulin sensitivity.
Calculating the Dose
You must calculate the dose of insulin to cover carbohydrates at each meal. The formula for this calculation is total grams of carbohydrate divided by "X". Your health care professional will tell you the specific number to use, as it is determined by your insulin sensitivity. As an example, if you plan to consume 60 g of carbohydrate at lunch and your personal "X" is 12, you will need to give yourself 5 units of rapid-acting insulin: 60 divided by 12 equals 5.
Considerations and Warnings
Diabetic management with insulin is a complex process. All calculations must be accurate and you must understand what you are doing to prevent giving yourself too much or too little insulin. Consult with a health care professional for the exact equations to use and with any questions and concerns you may have.
References
- Endocrineweb; Normal Regulation of Blood Glucose; The Important Roles of Insulin and Glucagon: Diabetes and Hypoglycemia; James Norman MD, FACS, FACE; May 2011
- Diabetes Teaching Center at the University of San Francisco; Diabetes Education Online; calculating Insulin Dose; 2011
- American Diabetes Association; Diabetes Care; Insulin Administration; 2002
