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Lights! Camera! Insulin Action!

How Insulin Action Impacts Blood Glucose in a MULTIPLE DAILY INJECTION (MDI) program

Before Reading This Article...
Before making any changes to insulin doses, it is important to understand the action of insulin (the onset, peak and duration of different types of insulin). Therefore, as background for the information that follows, we recommend you first review Insulin Types and Action.

Insulin is one of several factors that contributes to a given blood glucose reading at a certain moment in time. How insulin impacts blood glucose depends on the insulin action pattern of one of the three commonly used insulin programs:

  1. Conventional Insulin program
  2. Basal/Bolus Program with Multiple Daily Injections
  3. Insulin Pump Program

Remember, in the following text:

“long-acting” insulin refers to Lantus® or Levemir®;
“rapid-acting” insulin refers to Humalog®, NovoRapid®, or Apidra®

Basal-Bolus program using Multiple Daily Injections (MDI)

(Background long-acting insulin with rapid-acting insulin for meals)

The insulin action diagram for a Basal-Bolus/MDI program (above) shows that the blood glucose at a given time is affected by a certain previous insulin dose (follow the curve back) as follows:

Blood glucose before breakfast tells you about Morning long-acting the previous day (or bedtime long-acting, if applicable)
Blood glucose before lunch tells you about Morning rapid-acting
Blood glucose before supper tells you about Lunch rapid-acting
Blood glucose at bedtime tells you about Supper rapid-acting

For example, if the breakfast blood glucose is consistently out-of-range (high or low), you may want to change the morning long-acting insulin (or bedtime long-acting, if it’s delivered twice per day); if the lunch blood glucose is consistently out-of-range (high or low) you may want to change the dose of morning rapid-acting insulin

Next Steps on how to make adjustments to insulin doses in an MDI program:
MDI-Pattern Adjustment
MDI-Basal Bolus Approach


The above information was adapted with permission from The Alberta Children’s Hospital Diabetes Clinic information handouts.

The above information was reviewed for content accuracy by clinical staff of the Alberta Children’s Hospital Diabetes Clinic.

This material has been developed from sources that we believe are accurate, however, as the field of medicine (in particular as it applies to diabetes) is rapidly evolving, the information should not be relied upon, as it is designed for informational purposes only. It should not be used in place of medical advice, instruction and/or treatment. If you have specific questions, please consult your doctor or appropriate health care professional.

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