Offsetting Carbohydrates: Bolus Insulin

To properly administer meal-based bolus insulin, insulin to carbohydrate ratios must be established for the patient. The I:C ratio is the amount of carbohydrate that will be controlled by 1 unit of insulin. For example, if a patient has an I:C ratio of 1:7; one unit of insulin will be sufficient to control the raise in blood sugar caused by 7 grams of carbohydrate. An I:C ratio is considered appropriate if it returns blood sugar levels to the pre-meal value within 3-4 hours after eating. I:C ratios are very individualized and may vary from meal to meal.

 

Optimal Basal/Bolus Programs

While we still have options for creating a basal/bolus program, the bottom line is that both are needed to keep glucose levels as close to normal as possible. 

Basal insulin is best administered through either an insulin pump or injectable basal insulin formulations, while bolus insulin is best provided through the use of rapid-acting insulin analogs.

 

Basal-Bolus Insulin Therapy

The orange line in this graph illustrates the typical insulin requirements throughout the day. This need can be met quite well through the use of a basal/bolus insulin approach.

 

Insulin Delivery Methods

Delivery by syringe needle

Delivery by insulin pen

Delivery by insulin pump

 

Insulin is injected subcutaneously, usually into the abdomen, thighs, hips, arms, or buttocks.

A number of options are available for delivering insulin:

Traditional syringes can be used, by drawing insulin out of a vial. 

Insulin pens contain a prefilled cartridge of insulin. The user turns a dial to the desired dosage and presses a plunger to deliver the insulin. A disposable pen needle is changed after each injection. 

An insulin pump contains a reservoir of rapid-acting insulin. A drive motor delivers the insulin, which is then injected subcutaneously. The pump delivers a steady rate of insulin (the basal) and can be programmed to deliver specific amounts at mealtimes (the bolus).