When does the extended dose start working? Is it immediately or one hour after the bolus?

The extended or square dose starts to work at the same time the insulin peaks.

If you are using rapid acting insulin, the insulin takes approximately 5 to 15 minutes to start showing up in the blood stream and peaks approximately 90 minutes later. An extended, or square bolus slows the insulin dose over time, so the insulin peak is extended over time following the dose and timing. If you look at the insert in your vial of insulin, you can see the insulin concentration in the blood after administration over time. The extended or square bolus extends the curve.

You decide how much insulin to give and the timeframe you use with your medical team so how long the curve is extended depends on the length of time the insulin is delivered.

People use the extended, dual or square bolus for foods such as pizza, pasta and fast foods when they notice a pattern of high blood sugars 2 to 5 hours after eating those foods.

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